Sailing in the Lowlands Low is in McCall's book, Irish Fireside Songs. See Here. 
Kelly from Killann is a few pages later. As you can see, a tune reference is given for Lowlands, Joyce's Old Irish Music & Songs, #182.

Apparently a number of McCall's poems were set to music by Arthur Darley, using traditional Irish tune sources (hence the Joyce reference, I assume). I don't know if this as Darley's suggestion or not. Other examples are Kelly (no tune suggested in the book), Boulavogue, and Follow Me Up To Carlow.

I don't know where, or if, the Darley arrangements were published. I'd certainly be interested to find out.

Best to you, Bob.

John Roberts