Just answered a question today about where the wires attach to the starter and figured it might be good to add to this FAQ.
Here's where the wires attach to the starter assembly:
Originally Posted by mncdriver
Question, what source wire did you use for the 12 power and switched under dash?
Here's a diagram to help locate the 12V switched wires in the computer harness:
Per the instructions provided by Howell, you can retain either the #1 or #57 (yellow) wires to power the TBI computer. This is how I wired up my 12V power. If it doesn't provide enough direct voltage, it can be still be used to trigger a relay as like what timatoe did with his setup.