I would think the 98 would probably be the easiest year, as it dosent have the marker and turn signals in the bumper.
I dont know the steps to remove it, but I'm sure some good weaseling with a flashlight and you'll find something out. I'd imangine the grille, headlights, and other parts would have to be removed first. There is also a good amount of plastric rivets or other devices attaching it from the bottomside too.
Maybe this will help, maybe not, but heres my '96 with the bumper removed after being broadsided by an F150
http://img.photobucket.com/albums/v4...7/P1070072.jpg
But I will recomend to try Keystone for an aftermarket bumper replacement.
Depending on a damage, you might need a new bumper too, not just the cover.