This has always been my understanding of the text with all of the written phonetic accent (to my Standard american english ears) removed, but not the slang.

As I came in by Fiddichside, on a May morning
I spied Willie MacIntosh an hour before the dawning

Turn again, turn again, turn again, I bid you
If you burn Auchindoun, Huntly he will head you

Head me or hang me, that shall never fear me
I will burn Auchindoun thought the life leaves me

As I came in by Auchindoun on a may morning
Auchindoun was in a blaze, an hour before the dawning

Cawing, cawing, for all your crows cawing
you burnt your crop and tint your wings an hour before the dawning