A switch would replace the fuse, so use those two wires that currently (small pun intended) go to the fuse to install a switch.
I think it is a bad idea though; it is a failing switch that causes the problem in the first place and adding another switch into the mix is two steps in the wrong direction. That is why I use a fuse in the first place, a greased fuse inside a waterproof enclosure is virtually fail- safe. A switch will absolutely fail, speaking statistically here, sooner or later. And if a switch in the bypass harness fails, you will be in even worse shape than not even having the bypass in the first place- the bike will be just as dead and stuck but you will have no way to diagnose it other than removing the harness entirely.
A lot of careful thought went into that harness and trust me, the fuse is not used as any kind of shortcut or in an effort to make the harness less expensive. The very best materials and components (some are OEM but the wire and terminal crimping / sealing are superior to OEM) are used to prevent failures, not to be easy to build or as inexpensive as possible.
As far as fixing the original, if you have a good Kawasaki dealer within reach, it would be worth contacting them about this issue. They have been repairing these, at least in some instances, even on bikes long out of warranty. This problem is due to a bad design and a cheaply made switch in the first place so it is Kawasaki's problem and they have been quite good about taking care of them as they crop up.
Brian
Hey Brian-- your bypass switch solution has saved me but I have not had the time to pull out the ignition switch to fix it yet. Since I'm using it constantly, what would you recommend as an actual switch I can install inline rather than removing/inserting the fuse? And how to install, ie which wires to use/cut?
Thanks,
Robert