On my sons 99 TJ, some of the rear flare fasteners use blind nuts on the backside that you can't easily get to w/out contortioning your hands into the backside of the fender area, working around teh plastic trim pieces that are in the way. Biggest pitb I had on his was getting all the black widows out from behind the trim pieces Before sticking my hands up in there.
overall it was easy though. post pics of how the flares come out. though we will soon be mounting up steel tube flares and flat fendered fronts, I Was thinking about doing his flares until then.