1) Open the glove box all the way for under-dash access as outlined in this hack
2) Find the centra locking module. It's a black box strapped to the back of the big silver PCM canister on the passenger side wall behind the glove box.
3) Locate the Green wire with a white stripe on it. Cut it with wire cutters. You may tape the ends of the wires up, and close the glove box if you want. Optionally, you may install some extra wire and a switch (highly recommended)
Installing the switch:
1) Solder wire to the ends of the green/white wire you cut.
2) Solder the other ends of the wires up to the toggle switch from radio shack
3) Drill a hole where you can mount the switch. I chose to drill the hole in the upper back wall of the glove box, so that I can open the glove box and flip the switch easily.
4) Mount the switch in the hole you drilled
5) Close the glove box and flip the switch to the OFF (Open Circuit) Position.
When the swith is "OFF" or the wires are cut and not connected to any switch, this hack is active:
When the switch is "ON", the car will act like normal.
Care should be taken to make sure the trunk or hatch are not opened while driving. Even partially open (halfway latched but not sealed), they allow carbon monoxide into the car, which may or may not be accompanied by the normal exhaust smell. Also, contents of the trunk area may be lost, damaged, or cause accidents on roadways.
Thanks to Muzz on the focaljet.com forums for info on which wire is the ignition-on lockout to the CLM.