Here's a better write up of this.
What you need to do this is:
1 Set of Lite N Boltz 19.95
I found mine on ebay.
2 Radio Shack RS# 271-0120 8 Ohm 20 Watt Power Resistors
2 Superlite SL4000 4" LED Stop/Tail/Turn Lights w/ flanges 24.99x2
1 Cheap Pair of driving lights or fog lights CHEAP
1 Tube Hi Temp RTV Silicon FREE (already in garage)
Rat Tail File
1. On the LED wiring harness, add your resistor by soldering it to both the Red and white wires. Attach about half way down each wire so that the bare ends are still open. Do this for both lights. Use solder and cover any showing wires on the resistor with the RTV. Put aside to dry.
2. Remove your old tail lights.
3. Place duct tape over the area to be cut. Use one of the flanges as a template, mark the area. Cut your holes. Use the rat tail file to file down any sharp edges so you don't slice yourself open later.
4. Remove your license plate bracket. Size up your plate and mark the area for the new holes. You will have to move it to clear your tailgate. Drill your holes.
5. Cut the wiring off of both old tail lights so your have bare wires on one end and the connector plug on the other.
6. Mount your license plate with the Lite N Boltz. Run the wires up and out of your new brake light hole. Let them hang for now.
7. Now grab your new wiring harness with the resistors installed and wire it up to the old wiring harness that you cut off the old tail lights.
Driver's Side Wiring
Black/Yellow = Tail Light
Purple/Black = Backup lights
Green/Red = Stop and Turn
Passenger side is the same except that the Stop and Turn is Brown/Red
8. On the driver's side, splice the red wires (+) on the Lite N Boltz into the Tail Light wire(Black/Yellow) on the modified harness. Run black to a ground.
9.Run the white wire on the NEW harness to a ground and plug in the new modified harness to the old connector.
10. If you're installing backup lights as well at this time, run the power wire for the backups to the Purple/Black wire on the wiring harness.
11. Put the LED's into the flanges, plug them into the harness, and slide them into the holes. Use sheetmetal screws to hold everything in place. You're done. Woot!
Solder all connections and wrap them in electrical tape just to be safe.
***Note, 2003+ TJ's will have to relocate the evap canister on the driver's side by the tail light in order to make the hole.
Other things to keep in mind:
Making the holes too small at first is better than making them too large.
Make sure you aren't going to cut into anything you don't want to, before you start to cut.
Putting duct tape over the area you are going to cut or drill into leaves less chance that the saw will slip and scratch your Jeep.
Painting the open metal of the fresh holes with clear coat is a good way to keep rust away.