Adding a fuel pump switch is a simple and dirt cheap way to add a layer of security to your beloved ride. Note, this will not stop your car being broken into. A thief will rip open your ignition and turn your car on, and with the switch in the off position, your car will stall out within 5 seconds. Without knowing where the switch is located to turn the fuel pump back on, the only way to move the car is to tow it.
List of parts:
2 way switch rated for auto use (preferably non-lighted)
30 feet of wire (i wouldn't go smaller than 16 guage)
Wire strippers
electrical tape
drill and drill bits
Procedure:
The first thing to do is pry up your back seat to access your fuel pump.
Check your car's manual to see which wire is the power wire. On my car the wire is yellow with a green stripe. Seperate this wire from the rest and cut it, making sure you have enough wire to work with and to strip 1/2" from both pieces.
I then cut the 16 guage into 2 sections of 15 feet so that you can mount the switch where everyou want. Twist all the wires together and try to start your car.

If it starts and dies immediately, flip the switch over to it's other side and try again. If your car still does not run, you have a loose connection somewhere or you have mixed something up.

It's always good to have a friend help you with installs and to troubleshoot, as two heads are better than one.
If you car starts and runs like normal, turn it off and wrap up all your connections with electrical tape and ponder where to hide your switch. Hide all you wiring and snap your back seat back into it's place. I chose to put mine in my glove box so i can reach it easily and it was an easy place to take a picture of.
You are more than welcome to find your own dastardly devious hiding place that would be the last place a crook would ever look. On a side note, when i lifted up the seat, i found about $5 in change, some casino chips and a small precious stone that looked like it fell out of a ring. My mom is taking it to a jewler to see if it's a real diamond.
