Spaw, I thought I would give you a kickstart with your ABCDEF tuning
CHORD of C Major in ABCDEF tuning = 310202
CHORD of F Major in ABCDEF tuning = 010310
CHORD of G7 in ABCDEF tuning = 202030
I realise that this won't enable you to play Black Mountain Rag straight off, but at least you will be able to strum to "Michael Row the Boat Ashore"