This is just a theory, but....
If you wired it to a momentary switch (push button, like starter buttons) I don't see why it wouldn't work. Here's what I find different though. It runs off of the TPS in order to determine when it is at WOT. When your car is at WOT, the TPS reads appros 4.45 volts. Or somewhere in that neighborhood.So, what i'm saying is, if you used just a momentary switch, wouldn't you have to reduce the voltage to it, or else you might end up frying part of the ZEX kit ?
Maybe I am missing something with my though..so if anyone can add...please do.