St John's Gospel skips fairly quickly over the Last Supper itself, and instead focuses primarily on those words and actions not included in the synoptic Gospels, starting with Jesus washing the feet of the apostles.
The New Advent Bible page has the Greek, Knox translation English and Latin in parallel text form. You can listen to the Latin here and the Greek here.
Here is the Latin:
Ante diem festum Paschæ, sciens Jesus quia venit hora ejus ut transeat ex hoc mundo ad Patrem: cum dilexisset suos, qui erant in mundo, in finem dilexit eos. 2 Et cœna facta, cum diabolus jam misisset in cor ut traderet eum Judas Simonis Iscariotæ: 3 sciens quia omnia dedit ei Pater in manus, et quia a Deo exivit, et ad Deum vadit: 4 surgit a cœna, et ponit vestimenta sua, et cum accepisset linteum, præcinxit se. 5 Deinde mittit aquam in pelvim, et cœpit lavare pedes discipulorum, et extergere linteo, quo erat præcinctus. 6 Venit ergo ad Simonem Petrum. Et dicit ei Petrus: Domine, tu mihi lavas pedes? 7 Respondit Jesus, et dixit ei: Quod ego facio, tu nescis modo: scies autem postea. 8 Dicit ei Petrus: Non lavabis mihi pedes in æternum. Respondit ei Jesus: Si non lavero te, non habebis partem mecum. 9 Dicit ei Simon Petrus: Domine, non tantum pedes meos, sed et manus, et caput. 10 Dicit ei Jesus: Qui lotus est, non indiget nisi ut pedes lavet, sed est mundus totus. Et vos mundi estis, sed non omnes. 11 Sciebat enim quisnam esset qui traderet eum; propterea dixit: Non estis mundi omnes.12 Postquam ergo lavit pedes eorum, et accepit vestimenta sua, cum recubuisset iterum, dixit eis: Scitis quid fecerim vobis? 13 Vos vocatis me Magister et Domine, et bene dicitis: sum etenim. 14 Si ergo ego lavi pedes vestros, Dominus et Magister, et vos debetis alter alterius lavare pedes. 15 Exemplum enim dedi vobis, ut quemadmodum ego feci vobis, ita et vos faciatis. 16 Amen, amen dico vobis: non est servus major domino suo: neque apostolus major est eo qui misit illum. 17 Si hæc scitis, beati eritis si feceritis ea. 18 Non de omnibus vobis dico: ego scio quos elegerim; sed ut adimpleatur Scriptura: Qui manducat mecum panem, levabit contra me calcaneum suum. 19 Amodo dico vobis, priusquam fiat: ut cum factum fuerit, credatis quia ego sum. 20. Amen, amen dico vobis: qui accipit si quem misero, me accipit; qui autem me accipit, accipit eum qui me misit.
The Douay-Rheims version:
Before the festival day of the pasch, Jesus knowing that his hour was come, that he should pass out of this world to the Father: having loved his own who were in the world, he loved them unto the end.  And when supper was done, (the devil having now put into the heart of Judas Iscariot, the son of Simon, to betray him,)  Knowing that the Father had given him all things into his hands, and that he came from God, and goeth to God;  He riseth from supper, and layeth aside his garments, and having taken a towel, girded himself.  After that, he putteth water into a basin, and began to wash the feet of the disciples, and to wipe them with the towel wherewith he was girded. He cometh therefore to Simon Peter. And Peter saith to him: Lord, dost thou wash my feet?  Jesus answered, and said to him: What I do thou knowest not now; but thou shalt know hereafter.  Peter saith to him: Thou shalt never wash my feet. Jesus answered him: If I wash thee not, thou shalt have no part with me.  Simon Peter saith to him: Lord, not only my feet, but also my hands and my head.  Jesus saith to him: He that is washed, needeth not but to wash his feet, but is clean wholly. And you are clean, but not all.  For he knew who he was that would betray him; therefore he said: You are not all clean.  Then after he had washed their feet, and taken his garments, being set down again, he said to them: Know you what I have done to you?  You call me Master, and Lord; and you say well, for so I am.  If then I being your Lord and Master, have washed your feet; you also ought to wash one another' s feet.  For I have given you an example, that as I have done to you, so you do also. Amen, amen I say to you: The servant is not greater than his lord; neither is the apostle greater than he that sent him.  If you know these things, you shall be blessed if you do them.  I speak not of you all: I know whom I have chosen. But that the scripture may be fulfilled: He that eateth bread with me, shall lift up his heel against me.  At present I tell you, before it come to pass: that when it shall come to pass, you may believe that I am he.  Amen, amen I say to you, he that receiveth whomsoever I send, receiveth me; and he that receiveth me, receiveth him that sent me.
The Mandatum ceremony re-enacted on Maundy Thursday each year has become very controversial in recent years. Accordingly, it is worth considering what the Fathers have to say on it, as reflected in the anthology contained in the Catena Aurea.
First, consider the setting:
THEOPHYL. Our Lord being about to depart out of this life, shows His great care for His disciples: Now before the feast of the Passover, when Jesus knew that His hour was come that He should depart out of this world to the Father, having loved His own which were in the world, He loved them to the end.
BEDE. The Jews had many feasts, but the principal one was the passover; and therefore it is particularly said, Before the feast of the passover.
AUG. Pascha is not a Greek word, as some think, but Hebrew: though there is remarkable agreement of the two languages in it. The Greek word to suffer being pascha has been thought to mean passion, as being derived from the above word. But in Hebrew, pascha is a passing over; the feast deriving its name from the passing, of the people of God over the Red Sea into Egypt. All was now to take place in reality, of which that passover was the type.
Christ was led as a lamb to the slaughter; whose blood sprinkled upon our doorposts, i.e. whose sign of the cross marked on our foreheads, delivers us from the dominion of this world, as from Egyptian bondage. And we perform a most wholesome journey or passover, when we pass over from the devil to Christ, from this unstable world to His sure kingdom. In this way the Evangelist seems to interpret the word: When Jesus knew that His hour was come when He should pass over out of this world to the Father. This is the pascha, this the passing over.
CHRYS. He did not know then for the first time: He had known long before. By His departure He means His death, Being so near leaving His disciples, He shows the more love for them: Having loved His own which were in the world, He loved them to the end; i.e. He left nothing undone which one who greatly loved should do. He reserved this for the last, that their love might be increased by it, and to prepare them by such consolation for the trials that were coming.
His own He calls them, in the sense of intimacy. The word was used in another sense in the beginning of the Gospel: His own received Him not. It follows, which were in the world: for those were dead who were His own, such as Abraham, Isaac, and Jacob, who were not in the world. These then, His own which were in the world, He loved all along, and at the last manifested His love in completeness: He loved them to the end.
Secondly, those present are the twelve, including the traitor:
AUG. He loved them to the end, i.e. that they themselves too might pass out of this world, by love, to Him their head. For what is to the end, but to Christ? For Christ is the end of the law for righteousness to everyone that believes (Rom 10:4). But these words may be understood after a human sort, to mean that Christ loved His own up to His death.
But God forbid that He should end His love by death, who is not ended by death: except indeed we understand it thus: He loved His own to death: i.e. His love for them led Him to death. And supper having been made, i.e. having been got ready, and laid on the table before them; not having been consumed and finished: for it was during supper that He rose, and washed His disciples' feet; as after this He sat at table again, and gave the sop to the traitor.
What follows: The devil having now put it into the heart of Judas Iscariot, Simon's son, to betray Him, refers to a secret suggestion, not made to the ear, but to the mind; the suggestions of the devil being part of our own thoughts. Judas then had already conceived, through diabolical instigation, the intention of betraying his Master.
CHRYS. The Evangelist inserts this as if in astonishment: our Lord being about to wash the feet of the very person who had resolved to betray Him. It shows the great wickedness too of the traitor, that even the partaking of the same table, which is a check to the worst of men, did not stop him.
AUG. The Evangelist being about to relate so great an instance of our Lord's humility, reminds us first of His lofty nature: knowing that the Father had given all things into His hand, not excepting the traitor.
Thirdly, the point of the exercize is to teach humility and mutual service:
THEOPHYL. The Father having given up all things into His hands, i.e. having given up to Him the salvation of the faithful, He deemed it right to show them all things that pertained to their salvation; and gave them a lesson of humility, by washing His disciples' feet. Though knowing that He was from God, and went to God, He thought it in no way took from His glory, to wash His disciples' feet; thus proving that He did not usurp His greatness. For usurpers do not condescend, for fear of losing what they have irregularly got.
AUG. Since the Father had given all things into His hands, He washed not His disciples' hands indeed, but their feet; and since He knew that He came from God, and went to God, He performed the work not of God and Lord, but of a man and servant.
CHRYS. It was a thing worthy of Him, Who came from God, and went to God, to trample upon all pride; He rises from supper, and laid aside His garment, and took a towel, and, girded Himself.; After that He pours water into a basin, and began to wash His disciples' feet, anal to wipe them with the towel wherewith He was girded. See what humility He shows, not only in washing their feet, but in other things. For it was not before, but after they had sat down, that He rose; and He not only washed them, but laid aside His garments, and girded Himself with a towel, and filled a basin; He did not order others to do all this, but did it Himself, teaching us that we should be willing and ready to do such things.
St Peter challenges the reasons for Jesus' action:
AUG. He did not refuse, because our Lord's act was above his understanding, but he could not bear to see Him bending at his feet: Peter says to Him, you shall not wash my feet; i.e. I will never suffer it: not for ever is the same as never.
ORIGEN. This is an instance, that a man may say a thing with a good intention, and yet ignorantly to His hurt. Peter, ignorant of our Lord's deep meaning, at first, as if in doubt, says mildly, Lord, do you wash my feet? and then, you shall never wash my feet; which was in reality to cut himself off from having a part with Jesus. Whence he not only blames our Lord for washing the disciples' feet, but also his fellow-disciples for giving their feet to be washed. As Peter then did not see his own good our Lord did not allow His wish to be fulfilled: Jesus answered and said to him, If I wash you not, you have no part with Me.
AUG. If I wash you not, He says, though it was only his feet that He was going to wash, just as we say, you tread on me; though it is only our foot that is trodden on.
ORIGEN. Let those who refuse to allegorize these and like passages, say how it is probable that he who out of reverence for Jesus said, you shall never wash my feet, would have had no part with the Son of God; as if not having his feet washed was a deadly wickedness. Wherefore it is our feet, i.e. the affections of our mind, that are to be given up to Jesus to be washed, that our feet may be beautiful; especially if we emulate higher gifts, and wish to be numbered with those w ho preach glad tidings.
CHRYS. He does not say on what account He performs this act of washing, but only threatens him. For Peter was not persuaded by the first answer: you shall know hereafter he did not say, Teach me then that I may submit. But when he was threatened with separation from Christ, then he submitted.
ORIGEN. This saying we may use against those who make hasty and indiscreet resolutions. By strewing them, that if they adhere to these, they will have no part with Jesus, we disengage them from such resolves; even though they may have bound themselves by oath.
AUG. But he, agitated by fear and love, dreaded more the being denied Christ, than the seeing Him at His feet: Simon Peter said to Him, Lord, not my feet only, but also my hands and my head.
AUG. Our Lord, mindful of His promise to Peter that he should know the meaning of His act, you shall know here after, now begins to teach him: So after He had washed their feet, and had taken His garments, and was sat down again, He said to them, Know you what I have done to you?
CHRYS. He shows us the greater, that we may do the less. For He was the Lord, but we, if we do it, do it to our fellow-servants:
For I have given you an example, that you should do as I have done to you.
BEDE. Our Lord first did a thing, then taught it: as it is said, Jesus began both to do and to teach (Acts 1:1).
AUG. This is, blessed Peter, what you were ignorant of; this you were told that you should know afterwards.