ive done this shindig while replacing the pinion bearings and races.. but a thought:
some one correct me if im wrong but doesnt the crush sleeve need to be replaced every time the pinion nut is loosened and/or removed? if so, then replacing the pinion seal is a little bit more involved because you'll need to take the carrier assembly and pinion gear out of the housing to replace the crush sleeve. if the crush sleeve does not need to be replaced, then please ignore the rest of this reply..
if the crush sleeve does need to be replaced, the task is not too hard, it just takes time.. about a day or two (especially if you're going to replace the pinion bearing races).. its not difficult, it just takes time and and a few tools..
you'll need torque wrench that can read down to 5 inch pounds as the torque "drag" spec on the pinion nut is i think between 8-14 inch pounds if you re-use the old pinion bearings and 16-29 inch pounds if you replace the bearings. if i can remember correctly, the pinion nut is 1.0625 (one and one sixteenth) inch in size... in addition, a breaker bar with an extension pipe will help u greatly to muscle the pinion nut to crush the sleeve (go SOWLY after you feel the crush sleeve engage the front bearing - and you'll feel it because the crush sleeve takes at least 150 foot pounds to crush... most people testify to over 200 foot pounds.. so all of the sudden itll be really hard to torque over).
while the pinion gear is out, it would probably be wise to get a flashlight and inspect the pinion bearings and races... look for any pitting and scuff marks and replace as necessary.
if the "rear" pinion bearing needs to be replaced, it needs to be driven off of the pinion gear, you can either get a bearing splitter tool or use a chisel or something "wedgy", just make sure you dont start cutting into the pinion gear's shaft with a chisel. there is usually one or more shims between the pinion gear itself and the bearing, keep this shim in a safe place and put it back on assembly as it sets the pinion depth.. the new "rear" pinion bearing will then have to be "pressed" back into the pinion gear shaft, go to a local machine shop and ask em to press it on.. i didnt have time to go to a shop so what i used was a large pipe and a rubber mallet... it doesnt take much force to get the bearing in, just go slowly and put some anti-sieze lubricant on the pinion shaft.
the "front" pinion bearing is easy to replace, just pop the old one out and pop a new one in.
if after inspection you decide to replace the pinion bearing races, you'll need a good punch set - a brass one is preferable as the new races can NOT be scuffed, or dented. it takes time to punch the races in/out so take it easy and have some lemonade on hand.
oh and i forgot
since you need to remove the carrier, you need to remove the axle shafts, search the board on how to do this, its a very easy process and takes about 20 minutes and a flaslight (remove the wheels, remove calipers, remove rotors, remove differential cover, remove cross shaft screw, remove cross shaft- dont turn the axle or carrier while the shaft is out, push axles all the way in, remove the c-clips, pull axle shafts out, put the cross shaft and its screw back in so the spider gears dont fall out, remove the carrier bolts with 0.75 inch socket, remove bearing caps, remove carrier, catch the bearings and shims, done)... if you're not going to replace the axle seals, try not to set any weight (weight as in the axle shafts) on them as this could damage them which causes leaks at the end of the tubes... oh, when you remove parts like bearings, shims, bearing caps and so on, mark them to indicate where they where they were removed (and on some parts, which way they were facing) and put them back in the same position on assembly.
i'm sure ive forgotten a few (or a lot) of things, so here's a good read on the 8.8 rear axle:
http://www.corral.net/tech/drivetrain/gears.html