This is an interesting question. And I’ve spent a little time searching, and I can’t find any good answers. I have found a hundred different tabs for “Blind” by Korn, but that’s not what we’re looking for.
I did find a site that has lessons to teach guitar entirely audibly, for the blind:
Music For The Blind Homepage
But that doesn’t address the issue.
I could see some potential, in a limited scope, for using a “coordinate” system. Calling out the string note and then the fret for a piece – So for a C major scale, you could call out
A 3 5 D 2 3 5 G 2 4 5
Or something like that. Obviously, once you get into sweeps and Syn’s etude stuff, that would present challenges. It might take two hours to read out one of the Etudes, but at least it could be a start.
Would it be helpful if I did a quick recording of something like that for one of the lessons?