[Zero10]

I did something along a similar line in a previous car.
I had a button you had to hold down while you started the car.
It was one of my home-made anti-theft devices. It would kill the fuel pump unless it was held down until the ignition switch was turned back to the on position from start.

Mind if I ask what your motivation for this is?
It would be pretty simple to do. Perhaps the sunroof switch is the best choice, since it's the only one I can think of that returns to the center position when released.
If you have a multimeter, just measure the resistance between pairs of pins until you find a set that is connected when you push the switch in the desired direction.