Thanks Stephan,
I had looked through the BKP schematics already, and the closest is the PRS switching system. However, I am really too much of a beginner at wiring to adapt that particular diagram.
I shall, however, check through the other links you suggest, especially the guitarnuts website.
As far as the build goes, I have already purchased the rotary switch and routed the pocket for it (never again shall I make an electric from padauk - the amount of irritating, getting everywhere, staining wood dust is ridiculous with it. Looks nice though :) ), so I shall leave the megaswitch for a future build. I already have a set of Irish Tours for my next attempt (am thinking a uk timber hollowbody), so perhaps the twin-neck following that one :)
Thanks for the advice,
Adam