The instructions for the amigo are pretty much exact. If you call up isuzu or go to autozone or advance auto you can get the bearing seals. I built the tool to take off the preload nut out of a piece of pipe, you can use a screwdriver and tap it as well (I think that's what tone did). I think after you have the grease and the seals (the $5 bearing grease tool is great) I think all the tools they recommend in that post are very useful, you don't need anything else... unless you find your bearings are burned.. each little cylinder looks scratched, then that's all you need. If the cylinders are scratched.. the bearings are covered under warranty, just put everything back together and head to the dealer for a free bearing repack... that's what I got with 70k... oh, and I have the 10/120 warranty though, not sure about 99's status now on that...
This is totally a job you can do if you change your oil, do your spark plugs.. basically if you like to work on the car. Well, it's much more difficult but it's not rocket science. I wouldn't attempt to install a super charger or anything by myself, but I've done this one alone. It's very dirty, and the first time took me forever, but each time after that has been simple.
Post any questions and I'll watch the board...