You aren't going to find anything saying "this color wire goes here"
This is as close as you're going to get unless someone else is willing to take the time to use this info to draw a diagram for you:
(you should be able to do it yourself though)
There is a diagram right there on the A-Pac page (
http://www.ultimarc.com/a-pac.html ):


The zig-zags on the diagram are the potentiometers and as you can see, they each have 3 wires connected to them. If the gun works backwards, reverse the two outside ones. Don't forget the calibration steps I mentioned in the last thread where you asked about this. Ignore the LEDs and coils(solenoids) for now.
I'm in the process of fixing up a set of beast buster guns. I'm working 60hr weeks, so I doubt they'll be done anytime soon. But when I get everything hooked up (including feedback using mamehooker), I will post a tutorial.
Attached is a list of games that used positional guns.
(not all the games that used optics instead of pots are marked yet, so don't use this list as a positional gun buying guide. Guns from games like operation wolf & mechanized attack won't work because they used optics like a real light gun instead of pots)