Funny enough, I'm using one right now, as my key-driven ignition switch kinda self destructed a couple weeks ago. It's only temporary in my case, but it works.
The wiring part is easy, as you just need to use the 4 wires that come off the back of the ignition switch. One is the power feed. One goes to the accessory portion of the wiring. One is for the Ignition power. The last one is for the starter. Optimally I would go with a 3 position rocker switch and a push button. This way you get the ability to use the accessories separately like a key would allow.
Were you looking to totally remove the key setup? Or still use the key, but have the pushbutton for the starting?
My oil line fix
My 100k stopped odometer fix
Brace for impact, I'm in a "modifying mood". Massive thread count inbound.