i just installed my backup camera on my 99 limited last weekend.
it sucked.
but...in order to get that plastic piece off of the hatch....use a flat head screwdriver with tape on it to pry it off.
first, pop off the plastic piece under the rope pull, and unbolt that bolt.
then, start on one of the corners of the plastic panel, and use the flathead to pry it off, you will hear it pop off. there are pop rivits on the bottom, and the two sides. The top of the plastic panel is attached to the window itself. you just have to push up on the plastic piece (or....slide the plastic piece parallel to the window) it will slide up about 3 inches or so and then you can pull it off.
then...you should see your backdoor ECU. it is an orange box with 2 (i think 2) connectors attached to it. JUST LEAVE IT, do NOT disconnect this. there are a number of 10 mm head screws around a black metal piece. unscrew all of these. then there are 3 pop rivits (white colored) on this metal piece. pull it down, and let it hang from the wires to the back door ECU.
now you can see inside of the hatch.
i mounted my camera underneith the license plate....above the rear hatch latch. when you look inside the door...the camera is RIGHT above the rear latch. I then ran the power and video wires along the stock harness, up the drivers side of the hatch.
just use a cable to fish the wires up through there. DO NOT use anything metal, because you can cut the stock wiring. i used a piece of CAT5 networking cable since it is pretty stiff stuff.
once i had it through the door, i fished it through the rubber grommet connecting the hatch to the vehicle body itself. now the wires are in the vehicle. i ran the wires along the headliner on the side (under the plastic on the drivers side)
i know this sounds hard....it really is not...i just takes forever.
its hard to explain in writing, and is pretty self explanitory when you start digging in.
if you have any questions...just ask!