I replaced the stock signals with some shorter stem pieces a couple weeks ago. As I recall, the right pos was a green/red wire and the left was a green/white? They both used a separate neg, black I think, but I didn't worry about it because the schematic said they went to a common ground. If you're using halogens, I don't see why it would really matter which wire on the light you choose to make pos. I'd be more concerned about higher current draw from a halogen.
