I put mine on my 98 a few months ago, its pretty straight forward.
Remove the caps, bumper, and all brackets including the riveted cap brackets on the lower quarters.
I had to remove my hitch(ditching it anyway), and prop up my gastank skid. I then removed the nut strips to cut them in half, then reinstall the front portions for the gastank skid. You do this to allow use of the 'mini' nut strips Mark provided for the bumper.
Slide the Mini strips in and loosely bolt them up(you want them snug up against the bumper before tightening at the rail).
Now the best part, slide the bumper on. You might have to give it a hip shot a few times to snug it up.
Start installing the 10 bolts at the old bumper bracket mounts, but dont crank on them yet. (8 total of these for the brackets plus one for the Mini strip, bolts are provided, but suggested to double nut those. You can reuse the originals also with out the double nut suggestion).
Check the bumper is straight, and lined up(it will be, or very close), and if you got the carrier, temp it on, and check your lift Gate clears(take note of the space the gate has as it passes the carrier bushing) Adjust bumper as needed before tightening the bolts(the top ones can be a bit of a pain to get a socket on). Use a Jack if you have to move it around a bit.
After you are satisfied torque those bolts tight, then the same to the mini strips, at the rail.
Next is dealing with important lower quarter bolts. I had some rust issues to deal with to make that area a useful connection. But you may be able to just create access to inside the lower quarter so that you can bolt the stainless Allen heads, and small plates provided through the quarter guards of the bumper and onto the quarters.
Was a few months ago, but thats how I remember it.