Ok, I did some more digging last night. Since some other folks have the same questions, i'll post what I found out.
I couldn't find anything specific, but I did find this on a Camaro/Firebird forum:
The photo eye works in the following manner: When the "eye" detects light, the resistance is zero. As it gets darker, resistance goes up. When the resistance gets to a certain point, the voltage will drop below a preset level, and <CLICK!> the lights come on. If you put a switch in parallel (or just cut, strip, and tie the wires together), the resistance will stay at zero, and your lights will stay off. Note that you can NOT just cut the wires.
Here's a quickie diagram:
http://www.mloakley.com/images/auto-headlight_bypass.jpg
I'll give it a try this weekend and let y'all know what happens.