There should be a spade connector sticking up from you ignition coil. If this connector is connected to the engine crankcase with a wire - your ignition will not work.

Therefore, to connect a switched wire to this spade connector on the coil with the wire on the other side of the switch connected to the crankcase is what you want.

Tower sells one somewhat like this but it also has a micro switch that can be closed with a servo arm. I don't know if that was what you were talking about or not?

http://www3.towerhobbies.com/cgi-bin...XJ776&P=ML