Is it possible to run the halos and leds in the projectors to a switch? How hard would this be... has anyone done it?

its very easy, we did it to a friends civic with the halos to a cheap pep-boys switch. It's pretty easy, just simple wiring, I don't remember all of the specifics but if you're comfortable with wiring its a breeze

it would be as simple as powering anything else. power+ground+remote=power to halos