Hope this helps, as it's 3 months late;-)
I'm getting lots of experience trying to keep ~my~ 2000 Focus on the road.
Books recommend removal of entire drum/backplate/ hub assembly by removing 4 bolts from rear of backplate.
However, you'll find access to at least one of these bolts obscured by the shock absorber.
In reality, the best way is to remove the dust cap over the axle nut (you'll need a small screwdriver to work out the dust cap). Once the axle nut is exposed, arm yourself with the correct socket (I think it's 31mm) and a 1/2 inch drive ratchet and go to town. The axle nuts are specially designed to be self-retaining; they will come off smoothly, but will not *break* like a regular nut.
If you're careful, you can remove the hub/drum from the spindle without damaging the bearing.
However, it's worth spending some money on new bearings, as rear bearing quality was yet ~another~ problem with the early Focus.
You'll have to have to the new bearings pressed into the drums...not a shadetree project, as the tolerances are close.
Also consider new drums, depending on how early you're catching your rear brakes.
New drums, about $30 each.
New bearings, about $50 each.
Brake shoes, about $20.
Doing it yourself, to make sure it's done ~right~....
....priceless!
Best Regards,
Craig
Craig Nienhuis, January 2006