Prodigy Brake Control and 2003 Toyota Tundra

I received my Prodigy brake control from RVWholesalers.com.  Thanks for the reference!  I was wondering if any forum member with one of these  and a Tundra w/factory tow package (or anyone else with some experience with these things) could please give me some help with the wiring as the Prodigy instructions do not include the Tundra.  My 2003 Tundra w/factory tow package has a 5 wire brake control jumper harness that plugs into a female service connector for a brake controller with following set-up:
1.Black w/red stripe-fused trailer brake controller battery feed
2.Green-headlamp switch to vehicle trial lamps
3.Green w/white stripe-vehicle stop lamp switch to brake control(input)
4.Brown-Trailer Ground
5.Red-trailer electric brake feed from brake controller(output)

This harness has bare, loose wires that connect to the  Prodigy's 4 wires:
1.Black-Positive Battery
2.White-Negative Battery
3.Red-cold side of stoplight switch
4.Blue-brake output to trailer

Some of the connections are no brainers but the Prodigy instructions don't cover the Tundra.  Specifically the green "Headlamp Switch" and the brown "Trailer Ground" wire on the Tundra harness mate with what on the Prodigy?  The Trailer ground  is an ~#18 gauge wire and does not look sufficient to carry the level of current I would expect may be needed.  I can connect the white Prodigy wire to the negative terminal with #12 gauge wire as per the instuctions and splice the trailer ground wire into it.  I'm totally in the dark with the green headlamp switch connection (pun intended).  As you all can probably tell this is my first attempt at this kind of thing and need some expert advice.

Thanks in advance for any assistance!
Mark