Help, disability requires adding a dash mounted START switch
 

My wife's arthritis is making it very hard for her to start our 2003 GM. Getting the ignition switch to the on position is not a problem, but it seems this vehicle has a very hard and awkward ignition switch 'START' position for a physically challenged individual. My idea is to just add an aftermarket N/O switch. I will supply +12v ignition voltage to one side of the switch, the other side of the button would splice into the ignition 'START' wire. So she can insert the key/turn the ignition on/ then push the start button till it starts and release the button. Turning off the key will stop the engine. This is a manual start setup requiring the correct key chip and turning the ignition on, nothing like the newer buttons in later vehicles. I have done some searching and it looks like this car has a single red/lt blue 'start' wire coming from the ignition switch that I would splice the button output into. Problem is I can not find a schematic or wiring diagram of the ignition circuit to insure this is correct. Any other ideas or links to schematics that will help me will be appreciated.. Thanks, Bob D.