I did a writep on homemade elec RS headlights with a toggle several years ago and it was posted in the stickies, but the previous elec mod deleted them when he got demoted.
The wiring is pretty simple. Ted is correct - single pole double throw momentary toggle switch from Radio Shack. Get the spring-loaded version (that's the "momentary" part, I believe) Switch is just a few bucks.
In your case - since the wiring appears to be hacked already - you'll have to disable all of the relays, limit switches, etc and just deal with the two wires that operate the motors. Switch the polarity and they turn in the opposite direction.
Once you've found those two wires from each motor, wire the two motors together temporarily. At the temporary splice, hook your battery charger to them and see if they're doing what you want them to do. Specifically, are both doors opening and closing together? If one is trying to open and the other is trying to close, just reverse the wiring.
Please don't laugh at my wiring diagram.
Run two wires from the splices into the pass compartment, and then wire the toggle per the diagram. Push the switch one direction and they close, push it the other direction and they open. The switch and the wiring is responsible for the polarity change which reverses the direction of the motors. The switch is spring-loaded back to center, which is the "off" position. Be sure and use an inline fuse on the wire running from your 12V source to the switch. You can use a "key on" or "always hot" source for your 12V, your choice.
This system, while admittedly a bit hokey, has worked well for me for years. I DO have a control box which will activate the system by using the headlight switch (courtesy of Mat Klemp), but haven't gotten around to installing it yet. I hid the toggle in the ash tray.