Actually what you're probably looking for is a starter disable (dead man switch for me is something that gets released when you go: kind of like what terrorists hold when they're wired to explosives, or how the motorcycle looses gas when you let go of the handle).
Anyways, if you have an automatic, it might be as simple as tapping into the NSS (neutral safety switch) or for stick shift into the clutch pedal switch.
I wired a fuel pump cut off switch and hid it in a reachable position. I located the fuel pump relay under the hood and I think I cut the power lead to it (it's been a while) and ran the wires for the switch around and through the firewall in an inconspicuous manner. but it isn't fool proof, someone could eventually find the switch or locate and splice the wires but it would prevent a qick theft.... I never used it when I parked at work untill after my XJ was stolen from there. Also I always forgot to switch it again before starting. Now I don't get out or attempt to start it without hitting the switch first but (knock on wood) no body has tried to take it since i got into that habit.
I'd either tap a kill switch into the ignition module and/or fuel pump ckt, or rig a momentary switch in series (or bypassing!) the starter relay so you can't crank without hitting the switch. Of course, this won't prevent jumping the starter leads, but there's your quick theft protection.
How involved you want to get into this depends on you - I like having kill switches hidden where I can hit them on the way out with a fairly natural motion, but concealed so they can't really be seen without LOOKING or knowing where they are.
Another option is to put the switch in series with one of the sensors. There are many that can be used, including the camshaft and crankshaft position sensors. They will not allow the engine to be started when they are disconnected. It's safe and would be very difficult for a theif to track down.
I plan a fuel pump kill. I have a bunch of alarm sencors for doors that a building would use. The square thing at the top of doors. There is a magnet in one peice and a NO (normaly open) contact switch in the other. Mounting the contact switch inside center consul under change holder. Then just toss in a magnet when I want to drive. All wires tucked into the consul and a realy, a theif would have to tear apart the consul to find the switch. Just need to figure out how to keep it there when wheelin!
go to your local electronics dealer and ask them for a Starter Kill Relay. On most alarm systems they are installed so that a theif cant drive away with your car. you wioll need to hook up 4 wires. One to switches ignition power, one to each side of the starter wire and then also one to a switch that will have one side going to ground and the other to the input on the relay. This will be the most effectivce and easiest route to go. If you wire to your fuel pump then it is possible tha there could be a a small amount of gas left in there and it could stll be driven a little ways, with a starter kill then the rig will not even turn over.