From: Thomas A. Steahr (steahr@eng2.uconn.edu)
I had to do this same job my late '91 Integra GS. The side light assembly is a bit of a bitch to get off. The assembly slides *forward* to be removed, not sideways like would be expected. Remove that one screw and put the screwdriver away! I got the assembly out by smacking the palm of my hand against the lens in the direction the assembly comes out (toward the front of the car). This seems like it isn't enough force but keep at it for a while. I got mine out with about 5-7 minutes of smacking :) Seriously, if you try to pry it with a screwdriver I was afraid of cracking the lens. Use firm blows and try to wiggle it around every 3 or 4 smacks. I didn't try any oil (WD-40) as I was afraid to get it on the paint. That might be a last resort.

The owners manual shows a diagram of how the assembly is supposed to come out.