I should imagine that the words are given with the album insert (Happy Daze, Temple Records, 2001) but at a pinch you can listen to a live performance of the song at:  Prairie Home Companion, April 14, 2001

Though some sites credit the lyric to Karine Polwart, the text appears to be a slight re-working of that published as The Shepherd's Son in Herd's Ancient and Modern Scots Songs (1769), and printed by F.J. Child (English and Scottish Popular Ballads) as his version D of The Baffled Knight (No. #112), with a few verses omitted and a new final verse added.  Apart from the apparantly modern final verse, the other changes are pretty much of the sort that may have crept in in the course of traditional transmission.

Under version D, Child also placed the Northumbrian text published by Dixon in Ancient Poems, Ballads and Songs of the Peasantry of England (1846); Bell's revised edition of 1856 is available online at  Poets' Corner:

Blow the Winds, I-ho!  There are some significant differences, but the "dipping" episode is there, too.