In my recent piece on Chris’s sad passing and bass style, I put forward my half-arsed theories on his ’80s tunings.
I stand corrected, as the excellent video below shows. The whole thing is worth watching, but he gets into the issue of his five-string bass at around 12:10 (and also rattles off a nice demonstration of the ‘I’m Running’ riff).
Needless to say, his approaches to the five-string and tunings in general are as original as all his other musical ideas. Enjoy.