Mike,
I fabricated a hardwood spacer (in a U shape for the cables to run aft)that I mounted the ebrake assembly onto with four bolts. The hardwood spacer and ebrake assembly is attached to the metal strip the runs down the center of the Spyder with the same bolts. Other than having to re-engineer the handbrake mechanism, which is a new chrome VW replacement assembly, it was fairly straightforward and works fine.
I routed each ebrake cable through a pair wheel mounted on a steel plate I fabricated so each could change direction 90 degrees from fore-and-aft at the ebrake outboard to the brakes themselves.
Hope that helps.
Jim
ProSpyder