here is the conversion kit we sell (uses your stock switch housing in the tailgate):
http://www.bjsoffroad.com/prod-1346.htm
For jumping the brown wires, that is for bypassing the safety switch. note that if you do this, and have the tailgate down, the glass will still be able to go in and out if someone hits the switch (and subsequently the glass will break)
For the dash switch, if the tailgate switch goes bad, the dash switch won't work until the in-tailgate switch is fixed / replaced.
You can test like this:
1. try dash switch with key on. If no work, go to next step. if works, smile.
2. try tailgate switch with key. if no work, go to next step. if works, dash switch bad.
3. climb in back, remove tailgate carpet panel and remove access cover. find two fat brown / tan wires, and jumper them together to the motor. if no work, go to next step. if works, tailgate safety switch on driver's side of tailgate is bad, replace or leave out of loop (not recommended).
4. disconnect tailgate motor power wires, jumper to battery using alligator clips. If no work, tailgate motor is bad. if works, in-tailgate switch is bad, replace.