1. what i did was attach a light to the cap, drill through and pull two wires though (one hot, one ground)
2. i ran the wires down the inside of the cap, then out a small gap at the end of the bed. (the red wire is the hot for the brake light, the blue ones are for a dome light and a fan.)
3. next, i removed the driver side taillight for easier access to pull the wires down the side.
4. lastly, you need to crawl under the truck and find this connector by the spare tire. in the harness you will find a light green wire, tap the hot wire into this, and find an appropriate ground for the other.