What more do you need to know than that? Follow those dissasembly steps and you'll have stripped down the lower housing. Throw your old one out and include the new one in the build up.
The only extra thing I did when rebuilding mine was remove all the gears. This isn't a problem for the lower housing because the gears will come out when you remove the drum. On the upper housing you need to use a long punch to remove the gears that are staked in. I used a large c-clamp to press the stake and gears back in.
Any warn dealer should be able to get you the part. Check the exploded diagram for the number. I know
www.carparts.com also carries the parts, search the site with the part number.
Edit: I take part of that back. You will need to press out a bearing cap from the lower housing. The axle (for lack of a better word) that the brake uses rests in a bearing cap with needle bearings at the opposite end of the brake (drum side of housing). It is almost the same thing as a u joint cap. I just used a c-clamp and a socket to press it out. It was very easy. Then I regreased the needle bearing and pressed it back in. To remove that axle you just lift the drum retention plate up and pull the axle out towards the brake, that process is mentioned in Bill's article although he didn't do it.
(I had to completely dissaseble the winch housing so I could have it sandblasted.)
