Rear wheel bearing replacement on a Subaru is not a do-it-your-selfer job unless you are advanced and have equipment like a hydraulic press to take the wheel bearings out and put the new ones in. That said, I did my own but took the spindles out to a professional for the bearing change who promptly ruined them since he was not familiar with Subaru.
Since you asked in this forum, you should probably take it to a professional. Next best is to go get the Haynes, or similar, shop manual at your auto parts store and look over the procedure to see if it is within your skill and equipment level.
Added note (11/09/2009): I don't know for sure about the Haynes manual, but the Chilton is not at all helpful. It basically just says that forester owners should take the car to a shop.
The online repair guides on autozone are somewhat helpful, but still aren't very clear. I plan to change my own bearings, and will report back to this answer when I have done it. I understand that the job costs anywhere from 400 to 600 dollars so I personally won't be going to a shop. I understand that basically a hydraulic press will be needed and some type of pulling/pushing tool to get the hub out of the knuckle.
You sound determined. Try this:
www.endwrench.com/current/Current6/03/WhBearRep.pdf
Best of luck to you.
Apparently it is no longer recommended to use a hydraulic press. The hub is easily distorted. I made my own tool using 5/8 ready rod.
I got the outer bearing and having problems removing the inner?
rear wheel bearings are bad
The 2002 Subaru Forester has a 8 ft. 3.4 in. (99.4 in.) wheel base.
The 2012 Subaru Forester has a 8 ft. 7 in. (103 in.) wheel base.
The 2009 Subaru Forester has a 8 ft. 7 in. (103 in.) wheel base.
The 2003 Subaru Forester has a 8 ft. 3.4 in. (99.4 in.) wheel base.
The 2006 Subaru Forester has a 8 ft. 3.4 in. (99.4 in.) wheel base.
The 2004 Subaru Forester has a 8 ft. 3.4 in. (99.4 in.) wheel base.
The 2001 Subaru Forester has a 8 ft. 3.4 in. (99.4 in.) wheel base.
The 2011 Subaru Forester has a 8 ft. 7 in. (103 in.) wheel base.
The 2005 Subaru Forester has a 8 ft. 3.4 in. (99.4 in.) wheel base.
The 2013 Subaru Forester has a 8 ft. 7 in. (103 in.) wheel base.