I just removed my 91' LX's bumper a few months ago, let's see....
You'll have to remove the rear interior plastic trim panels to gain access to the nuts that hold the bumper cover on. I'm not sure exactly how many total, but there are several straight across the top, that hold the top of the bumper on that are easy to get to. Then there are a few on each side that are down in the sides that are more difficult to get to, especially where the gas filler neck is. Taking the taillights off will make it easier to see what's going on outside, but it's not totally nessesary. The bumper will then come off.
If your new bumper is just the Urethane cover, with no hardware (which it probably is) You'll have to take the mounting strips out of the old bumper. They are long strips of metal, one in the middle and one on each side, that have screw threads mounted on them. The nuts screw onto them from the inside. You'll have to wrestle with the old cover to get them out, but they'll come out with the help of a screwdriver or something.
Once you get the metal mounting strips into the new cover, slide it onto the car, fasten the nuts on from the inside, and tighten them finger tight ( or just not all the way tightened). Then you can push the cover around, bumping it here and there, until it's straight and the edges line up with the body, etc. Then fully tighten the nuts from the inside and re-install your interior panels.
That's it! Hope I didn't leave anything out.
Good luck with it!
