The switch needs to be a latching type – clicking the switch alternates between on and off – rather than momentary which is on when held down and off when released. I found the answer here:
http://www.voodoolab.com/forum/viewtopic.php?f=9&t=2914
I got a guy here is Australia (Bryce at http://www.loopipedals.com.au) to make me one and it works great.
Hope that helps – even though this thread is old.
