Here's a shortcut I use to replace the lightbulb, at least on my 1992 LS400. Basically, instead of removing the entire assembly, you access the bulb while the assembly is still in place.
Step 1: After pulling away the sidelight assembly, look inside. You will see the gray electrical connection and black ring that locks the light bulb.
Step 2: Looking down on the top of headlight assembly frame, you will see a rubber gromet, about 1" in diameter. Remove it. Will a light, you should see the top of the gray electrical connection.
Step 3: Remove the gray electrical connection. You can do this either through the opening where the sidelight was pulled out, or from the 'access' hold described above. I prefer to use a long flat head screw driver from the side.
Step 4: Reach in through the opening and untwist the black ring, and remove the bulb. (Tight fit, but it will come out. The left hand works best for the passenger side, and your right hand works best on the driver's side.)
Step 5: Put black ring around new bulb and insert back into hole. (I use latex gloves to avoid getting body oil on the bulb.)
Step 6: Put gray electrial connection on.
Step 7: Test. (If something has gone wrong, better to know now rather than after everything is reassembled.)
Step 8: Reinstall sidelight assemby.
