[wyatt]

I found my car's wiring diagram after MUCH searching online. It was in a manual for my car. It had a wiring diagram for the ECU (Engine Control Unit, the computer) and showed where the VSS, INJ, and many others were. I got under the dash, pulled the wiring harnesses off, and... they weren't the same as in the manual! I wound up jacking up the front drivers side tire and measuring ohms between each of the wires and ground while turning my tire. It worked, it was the green and yellow wire and the second to last one tried. You know it's the vss because the ohms will go from 0 to infinity and back several times during a revolution. I found the injector by comparing the color of the wires at the injector to those near the ECU and tapping into the injector from under the dash. My 12v came from the fuse box (though I think I may switch it to from the battery since I can't use my high beams with it) and my ground is just grounded to the chassis. I would guess I searched for the wiring diagram for several hours, and actually doing it with the method above took about an hour.

EDIT: I should add, the injector has two wires running to it, with the key on (not engine running) unplug the injector and measure both wires, one is 12v the other is 0v, tap the 0v one. Mine was yellow, maybe with a black stripe.
Also, I think these methods are covered in post #1 of the MPGuino page.