I swapped the front and rear diff bushings out in mine. Are you referring to the ones in position "9". The ones that the studs for the diff come through? (ignore arrows!)
If that's the case, make sure you have a full day set aside.
If the car is up in the air, you do not have to remove the diff. However, you will have to lower the diff enough to get the rear subframe out of the car.
- Remove the cover and bolts holding the driveshaft to the diff, move driveshaft out of the way. (leave attached to tranny)
- Next remove the inboard bolts for the F&R lateral links (mark the alignment cams first!).
- Put a jack under the diff
- Take the rear two diff studs out. Jam two nuts together on one stud, then turn the inside nut so it pulls the stud(s) out with it.
- Remove the 6-or-so bolts holding the front of the diff to the outrigger
- Carefully lower the jack to move the diff out of the way, leaving the half shafts in place. Keep some support on the diff (don't let it hang by it's shafts!)
- Remove the E-brake cable mounts from the rear subframe
- Remove the 4 bolts holding the rear subframe to the body
- Snake the subframe out from under the car
At this stage, the easiest method is to burn the old rubber bushings out with a torch. Remember, these were pressed in over 10 years ago. If you try to press them out you will only succeed in bending your rear subframe. Now, with the rubber burned out, very carefully use a hacksaw/airsaw to cut a slit in the metal shell that's left in the subframe. I cut a sliver out of the old shell that was about a pinkies width. The rest of the shell came out easy using a few light taps with a hammer and chisel. You CAN use a press to very carefully pop the new (greased) ones in. Make sure you get the orientation right, the new bushings should have an arrow on them. Or just take a picture of your old bushings before you start. When you're done, tape off the rubber bushings and prime/paint the rear subframe where you probably burned the paint off

Reverse to put it all back together paying attention to your alignment marks.
I would also suggest doing the front bushings (red arrow) at the same time since you would only be six bolts away from dropping the outrigger. The blue bushings should also be replaced as they are cheap. The blue ones are the ones that cause the "clunk" when you shift at high rpm. It's caused by the outrigger hitting the body on sloppy bushings. I used a combination of Avo and STi Group N bushings. You can also buy all of these from Turn-in Concepts (TIC).
Hope this helped!
Ryan