I'm not sure what year you are working on, and not sure if you are asking about the engine stop switch or if you are looking to install an aftermarket kill switch.

Looking at a wiring diagram, it appears that there is one wire that runs from the coil to the engine stop switch and also to the igniter, and one wire that runs from the coil to the igniter.  Let me state that I am not an electrician, I don't play one on TV, and did not stay at a Holiday Inn Express last night.  I am assuming that you want to install an aftermarket kill swithc, and I do have a theory.  I will run you though my logic real quick: the engine stop switch is basically a momentary kill switch that is connected to the coil.  If pressing the engine stop switch will shut off the engine, then installing a kill switch on the wire that connects the coil to the engine stop switch would have the effect of being a kill switch.

What year is your bike?