I used to own a GMC Sonoma and having the quadbeams (low and high beams at the same time) was a huge thing on their forums. I believe that it was Painless Wiring (I think that is their name) that actually has a kit to make this work at least on GM trucks. I don't know how different the headlight wiring is between GM trucks and the H3, but you might want to check them out. Here is a link to how it was done on the Sonoma without a kit. Again, I'm not sure if this will even work on the H3.
http://www.fmtc.com/~brule/quad.html