I changed mine through the rear wheel well. I didn't even have to remove the tire. Easiest way is to use a short headed phillips screw driver. If you sit at the rear wheel and look up into the wheel towards the rear, on the outermost edge are two screws that line the plastic trim piece and one screw in the middle of the liner on the rear wall (my memory doesn't serve me well on the number of screws, but this should be correct). Remove these and you will have some wiggle room to pull the liner forward out of the way which will reveal a white fastener with a large 10mm bolt through it. Remove this bolt and then you will be able to remove the white fastener that holds this portion of the rear bumper in place. Use needle nose pliers or a pry tool to pull the white fastener downward. Then you can easily pull the bumper off the "track" in an pulling outward motion. You can then get under the rear end of the car behind the tire and find another 10mm bolt which ties the bottom of the bumper to the chassis. This will allow you enough access to the rear side marker light. Twist out the bulb. Replace if needed. If replacing the entire marker, use a short stubby philips screw driver to remove the retainer screw that holds the light in place (very tight fit!) Remove from the entire unit from the exterior. 15 minute job total. Voilą!
The LED bulbs are white in color, however the lens itself is orange at the front and red at the back so when you put the LED bulb in it, it will still show the lens' color unless you have clear lens that you made or replaced it with, then you do need to have front in orange and red in the back.
I found that the LED bulb is not as bright as the regular bulb and since the color is not going to change, I replaced it with just regular 168 bulbs.
Pvong, I believe front markers must be orange (or white- up to officer's discretion), and rear must be red.
bb430 is correct, Tdedden, if you don't have clear lenses then it won't be much of a change IF you just get white LED's. They do make colored LED's. I do, however, disagree with bb430 on the brightness issue. My colored and white LED's are sooo much brighter than the OEM halogens. Also, since I'm using clear lenses, mine must be colored. If you choose white LED's in the stock reflectors, then not much change except increased brightness, but if you go with colored LED's in the stock reflectors then you'll get a much brighter color.
I've read in other threads that the LEDs don't last as long as the halogens, maybe the discussion was about a different light but I'm curious to know if any of you who have replaced standard bulbs with LEDs what your experience has been.