Since it seems like I'm the only one that's done it, don't get me wrong - others have, I know - just NO ONE during my search was able to provide exact details.
Ok, well... here goes nothin'.... my attempt at enabling the reverse lights in a "how to" thread.
I don't have a schematic book, so connections will be based from plugs and wire colors in my '87. And for ease of install... I cut the harness from the auto tranny (basically wanted to use the plugs).
In the attached pic, from left to right, you have the following:
1. 3 wire round plug, wht/blk spliced together enable the bypassing of the clutch (ie. pedal pushed in isn't required to start the car) and the blue is 1 of 2 wires needed for the reverse lights
2. 6 wire round plug, this plug actually tells the ECU which gear the car is in. If you searched for "auto cookie" you'll find some more info on what lead to the connections. Anyways, the only wire needed from this plug is the blk one (this is 2 of 2 for reverse wiring)
3. 6 wire square plug. not used for 5 spd. IIRC, it was linked to the 3 solenoids on the DS of the Auto tranny
4. 4 wire square plug, its a direct plug'n'play for car's with an ABS system.