police car style ignition bypass

I have a 77 Scout it uses standard GM ignition switch but now uses a ford solenoid that was installed during a complete rewire (ezwiring kit). It has also been fitted with a GM TBI (89 G20 Van). I know police cars have a switch that you can press then move the key to off, remove it, but still allow the car to run. If you hit the brake it turns the car off. All you need to do is reinsert the key and turn it to run and drive off. Does anyone have a basic diagram, or any input how to do it right. Thanks in advance

Easiest and safest thing to to would be to get an add on remote start module (the kind you add on to either a factory or and already installed aftermarket alarm) The remote start can be triggered by a negative pulse from the alarm (or in your case, a button you will mount). To shut it off you can either press the button again, or else press the brake pedal. With a remote start module, you could strt it without the key in the ign, or if its already running when you press the button, you can take out the key and it will continue running from the remote start module. You wire up the brake wire and a pinswitch on the hood for safety reasons. If someone tries to drive off(and presses the brake) it will shut down. If someone opens the hood, it will shut down, or not start in the first place if the hood is open.

use the basic remote start relay in the 12 volt remote start diagram on this website... it needs like 10 relays but it works.. i've used it... works great... press brake and shuts down...

I had a quick thought so here goes:- latching relay coil side neg via momentary switch i.e. the type you get with Viper alarms, other side of switch to ground. Latching relay- first coil pos, 12v+ perm. 2nd coil - perm ground, 2nd coil + from brake switch output. Feed input neg, ouput to normal relay 85, 86 and 87, 12V+ at 30amp  fused, 30 to ign 1. Please diode across between 86 and 85. That's it. If you have a secondary ign etc., just parallel in extra coils.

I've been on to Radio Shack site to give you a part number for the latching relay. Can't find it but you will find it on Maplin Electronics UK to give you some idea of what to look for. A god electronics parts store should stock them.