Need to tap into a live wire
 

I have a 2002 Mitsubishi Galant.
I need to power a hidden gps locator in the car which is something like a lo jack. It requires between 5v and 12v and preferably a wire that is always live.
It comes with a kit that has a fused set of wires, red and black. I assume the black wire should get attached to a bolt on the chassis, while the red wire splices into a live wire or harness port.

So far, the best wires for this seem to be behind and below the glove box. But... WHICH wire? I don't want to go setting off the car alarm or air bags.
I do have a multimeter, but I don't want to go cutting into wires, randomly guessing at which one will have live power.

If you want you can always go right to the battery, theres bound to be a grommet you can fit the wire through in the firewall.

That would work.. but...
 

It would have to be hidden better than that. The car is frequently at a mechanic because the car is a lemon. One thing after another goes wrong with it. I'm pretty sure the mechanic would spot that.

I did poke around with my multimeter a little. Unfortunately all I accomplished was making all the power locks in the car go nuts everytime I would poke a wire with the multimeter.

If youve ever looked at a universal fog light kits wiring harness, you have to go from the battery thru the firewall to your switch. If your mechanic will have a problem with that, theres a constant live wire fo memory to your radio, you could tap that. If you have an aftermarket radio, its the yellow wire.