Not sure if the quick and dirty method works but, if you haven't seen the thread I've linked below, the answer to the wiring question is below. I followed Patrick's instructions and posted on the second page with a couple things I did differently (mounting, not wiring differences). I highly recommend this as a permanent enhancement, as it's obviously nice to have 4 way flashers. Good luck with your inspection/registration.
Four Way Flashers -- How To with Pics