I can see this post was made almost 3 years ago, so you may never see this response, but, my god I've been singing this song since I went to Cape Clear years ago! I searched it on Google to see if I could find the correct lyrics and this post was the only thing that came up!
Now I have no guarantees the spelling is right either, (it was about 7 years ago now), but I'll give it a shot.

Spailpín óg bocht mise is imreochtach é mo shaol,
Táim óga, beagnach caite,
'Gus mo hairgeid go léir, cailte agam,
Ach mo lean, is ainnis iad na cursaí ma tá orm dul i gcéin,
Lie la lie.....

Nuair a dfhágas gach rud i mo dhiadh
Bhíos i mo ladín óg
Mar chairde ndaoine bhochta ar sráideanna sna bhailte-móra,
'Gus uaigneas orm,
Ach mar sin féin, nilím cailt nilím cailte,
Tá muiníneach asam féin!
Lie la lie....

That's how I've been singing it anyway, hope you see this!

Mags.