I just replaced mine (both) in my 2002 GS430. In the front right of the clear plastic you will see a little groove that will accept a small blade screw driver, GENTLY pry the plastic down and then front left, move to the sides and work the front down. Once you get this far it becomes clear since you can see the tabs. The rest is simply replacing the bulbs and reinstallig the plastic dome. Go slowly and avoid any gouges in the trim pice.
DD