Roadmaster has a kit with two diodes in it, E-trailer or Campingworld.com sells them.
http://www.etrailer.com/Accessories-and-Parts/Roadmaster/RM-792.html shows you what to look for.
Basically you cut the wire going to the right taillight bulb, connect the factory wire to one diode input, the bulb to the output. Then connect the right input to the diode's second input terminal. Do the same for the left turn.
For running lights, I tied into the factory wire at the front of my car, and feed the front running lights, and they all light up.
Ground is really simple, you just connect it to any part of the jeep metal framework.
You will have three remaining wires. You can use those for the braking system. In my case, I decided to run a vacuum line from my RV engine to a air hose, to the rear bumper. I connected this to a quick connect, to a vacuum hose to my Ford Edge, and to a second cruise control motor (from a junkyard Nissan car) mounted under my dash, and the cable going to my brake pedal and the floor. So when vacuum is applied to the second CC motor, it pulls the cable, the brake pedal to the floor, and applies the brakes in my car.
I also needed some check valves so that the power brakes are also run by the vacuum line, and a pneumatic valve (from the same junkyard nissan - cars have all kinds of 3 way vacuum valves on them that are energized with 12 volts). So when my brake lights come on (I had to run a wire from under the dash of my 97 Bounder, but if you have a third brake light, it will do the same thing) it energized the 3 way valve, applied vacuum to the brakes and CC motor, and applied them. All for about $35 in junkyard parts.
Good luck,
Fred.
