Not to toot my own horn, but I've started playing around with that technique about the time of Joe's birth trying to mimic a passage from Yes's "Sound Chaser" from the Relayer album, with my pre-pre-factory PRS, and I got pretty good at it....but nowhere near as good as Joe.
I believe Joe may have picked the technique up from Roy Buchanan, other than Joe, Pat Travers does a pretty cool one too on "I La La La Love You" and the long intro to his encore "Born Under a Bad Sign". Rockin' Ron and Silver Haze, chime in if ya hear me :-)
CarljMD
Takers get the honey, givers sing the blues