On one of my last visits to the library I got a photocopy of Vernam Hull's translation of De Gabáil in t-Sída. Seeing as it's now out of copyright, and I haven't seen the translation online anywhere else with the Irish along with it, I thought I might as well copy it up (not like I'm going anywhere anytime soon, at the moment...).
Anyway, the English is first, followed by the Irish, for reference. There are two versions of the tale, of different dates and linguistic styles but basically the same content. Hull's translation is from the older version from the Book of Leinster, which is probably ninth century in composition, and while he gives both of the Irish versions in the article, he only gives one translation so I've only given the relevant one (from the Book of Leinster):
Here follows the Seizure of the Fairy Hill
There was a famous king over the Túatha Dé in Ireland. His name (was) Dagán. Great, then, was his power, even though it belonged to the Mac Míled after the conquest of the country, for the Túatha Dé destroyed the corn and the milk round about the Mac Míled until they made the friendship of the Dagda. Afterwards, he saved their corn and milk.
Now when he was king at first, his might was vast, and it was he who apportioned out the fairy mounds to the men of the Túatha Dé, namely Lug Mac Ethnend in Síd Rodrubán, (and) Ogma in Síd Aircelltraí, but for the Dagda himself Síd Leithet Lachtmaige, Oí Asíd, Cnocc Báine, (and) Brú Ruair. As, however, they say, he had Síd In Broga from the beginning.
Then Mac Oac came to the Dagda in order to petition for land after it had been distributed to each one. He was, moreover, a fosterling to Midir of Brí Léith and to Nindid, the seer.
"I have none for thee," said the Dagda. "I have completed the division."
"Therefore let be granted to me," said the Mac Ooc, "even a day and a night in thy own dwelling."
That then was given to him.
"Go now to thy following." said the Dagda, "since thou hast consumed thy (allotted) time."
"It is clear," said he, "that night and day are (the length of) the whole world, and it is that which has been given to me."
Thereupon the Dagda went out, and the Mac Ooc remained in his Síd.
Wonderful, moreover, (is) that land. Three trees with fruit are there always, and a pig eternally alive, and a roasted swine, and a vessel with marvellous liquor, and never do they all decrease.
De Gabāil in t-Sīda in-so Sīs
Boí rí amra for Tūathaib Dea i n-Hēre. Dagān a ainm. Ba mór, di·diu, a chumachta, ced la Maccu Mīled iar n-gabāil in tíre, ar collset Tūatha Dea ith 7 blicht im Maccu Mīled con·digensat) chairddes in Dagdai. Do·essart saide, īarum, ith 7 blicht dóib.
Ba mór, di·diu, a chumachtasom in tan ba rí i tossucch 7 ba hé fodail inna side do feraib Dea .i. Lug Mac Ethnend i Ssíd Rodrubán; Ogma i Ssíd Airceltrai. Don Dagdu fessin, immurgu, Síth Leithet Lachtmaige, Oí Asíd, Cnocc Báine, Brú Ruair. Síd in Broga, da·no, ba laiss i tossuch, amal as·berat.
Do·lluid, di·diu, in Mac Oac cosin Dagda do chungid feraind o fo·rodail do chách. Ba dalta saide, di·diu, do Midir Breg Léith 7 do Nindid fáith.
"Ní-mthá duit," ol in Dagda, "Tarnaic fodail lemm."
"Etar dam, di·diu," ol in Mac Ooc, "cid laa co n-aidchi it trib féin." Do·breth do-som ōn, īarum.
"Collá dot dāim, trā," ol in Dagda, "ūaire do·romailt do ré."
"Is menand," olse, "is laa 7 adaig in bith uile, 7 iss ed ōn do·ratad dam-sa." Luid, do·no, Dagān ass, īarum, 7 anaid in Mac Óoc ina Síd.
Amra, da·no, a tír hī-sin. A·taat tri chrand co torud and do grés, 7 mucc bithbēo for chossaib, 7 mucc fonaithe, 7 lestar co llind sainemail, 7 ni·erchran and sin uile do grés."
From: Vernam Hull, 'De Gabāil in t-Sīda,' in Zeitschrift für Celtische Philologie Volume 19, 1933, pp53-58. See also: Paddy Brown's translation.