According to the NHRA rule book....

The switch must be on the positive side and stop ALL electrical fuctions.

This is to shut the engine off and prevent fires from shorted wires after an accident, the same reason you always see the fire department cut the battery cables on a car after a collision hard enough to damage wiring.

Why is it that a rule is put in place for your safety and then people have to try to find a way around it? These switches are a no brainer to hook up. Take the cable coming from the battery to one side of the switch, connect the other side to everything else (thru the starter relay or whatever).