Really easy to do
Ok, I figured it out.
To replace a burned out bulb for your P5 in the rear....you pop out those round things in the trunk. Stick your fingers way in the now exposed holes, you'll feel a nut. Take all 3 nuts out and the plastic on the outside of the car will pop out/off. Pull the burned out bulb out, pop a new one in, put the plastic piece back on, screw the nuts back in, put the hole covers back on and you are good to go.