The "lyric req" part is, I think, my mistake. I finally found the thread I was looking for, and this was in it:

The old Negro lore has it that the musician must 'take a black cat bone and a guitar and go to a lonely fork in the road at midnight'. The guitarist will soon be joined by an 'unseen musician' who will 'play in perfect unison' before taking his instrument away from him - although the sound will continue until our guitarist's fingertips bleed. 'The music,' runs the legend, 'will eventually subside, and when all is quiet, you may go home. You will be able to play any piece you desire on the guitar, but you will have sold your eternal soul and are his in the world to come.'

Even though it's been a few years, I'll try the e mail addy.........