The FSM would have answered this for you in 30 secs. Sticking a multimeter around on your ignition terminals would have answered it for you in 2 mins.
The ignition terminal (behind where you put the key in) has all the wires you need. The wire you'll want to tap at the harness connector (I wouldn't recommend cutting it, because soldering it back together under there is a biotch) is
black/white. It get's +12v through the 30A ignition fusable link when the key is on ON/START. You could use a relay setup and also tap the ACC wire (blue/white I believe) so that your boost gauge would be on during ACC/ON/START, but that's a bunch more work.
What that means is that you'll click the car to "ON", wait for the fuel pump to prime and for your boost gauge to 'self test', then start the car.
I take paypal, btw. $50/hr, and this post took 5 mins. Send $2 + 3% fees.
