I read through the instructions you emailed me, and it makes sense. Every time I think I have a clever idea it turns out someone already did it! Thanks for sending those. Per your diagram above, the switch essentially just completes the ground circuit as you mentioned in your previous explanation of the fact that the puddle lights are ground switched. So, in theory, if I complete that ground then the lights will come on. I think the only thing I'd want to do is a throw a relay into the mix, but as you have noted that complicates things since everything is ground switched. The rock lights I got are from Pro Comp, and there are 6 of them with 3 LED diodes per light. I don't think they came with a relay in the wiring harness, which indicates to me that the amount of current going through the switch they provide isn't very much (or at least not more than the switch can handle). I wonder if I could get away with doing this as simple as you laid out above and just tap the factory ground and run it to a grounded switch, and then wire the lights to the factory harness. I'm not real keen on that just because I'd like to have a relay handling the current, but maybe the lights aren't pulling enough power for it to be an issue? Are the DS and PS factory wires on independent circuits?
Just make sure the switch is rated for 10 amps as is the fuse for the lights. The driver and passenger are tied together, so if you tap the driver, both sides will come on.