The cheap easy way to do Footbrakes suggestion:
1. Get a standard 6' 120v extension chord and cut off both ends on one end connect both wires to the terminals on your switch on the other end put a shielded female blade terminal on one wire and a shielded male blade on the other.
2. Under the hood disconnect the coil power wire plug the male blade into the wire and the female to the coil.
3. Operate switch to test. Should have a working kill switch with no cutting of the factory wires.
4. Route the wire through the fly wheel through an existing grommet (there are plenty), and reconnect the switch (cannot feed through the fire wall with it connected - I tried).
5. Find good place to hide the switch. I recommend in the kick panel below the e-brake or between the drivers door and the sill plate. It cannot be seen, and you can even turn it on with people in the car and they will not know it (if you hang out with low-lives or give a stranger a ride).
6. Try to avoid putting the switch under the dash. It is the first place they look.
7. Buy a column lock so they walk past your car, and do not find out that you have a kill switch only after destroying your door and column.
Total cost (not including the column lock) about $4.00 (if you don't have the stuff lying around). I did this while at a friends house out of town in less than 20 minutes (really bad hood and a Monte kept driving by checking my car out when it was still black).