well, the koch tools subframe mount tool should allow you to do the bushings on the car; you basically would do this:
1. disconnect handbrake cables from handbrake
2. remove exhaust
3. remove driveshaft heatshield
4. remove driveshaft brace (the one that covers the two foremost subframe mount bolts) and heatshield on top of it
5. disconnect driveshaft from rear diff
6. support rear diff/subframe with jack
7. unbolt subframe from car
8. lower subframe down so that it clears the front studs (the two front subframe bolts are studs, and like 4" long!)
9. use koch tools subframe mount tool to remove old rubber mounts
10. install black AKG subframe mounts (best design that i could find - they fit totally flat against the floor, helping to distribute the load over a greater surface area)
11. raise subframe assembly and bolt back up!
12. reassemble
now, since you're swapping you diff out, you would remove it at step 5. with the diff out of the subframe, you might want to build a crude 'spacer' out of 2x4 scraps to put in place of the diff, for raising/lowering the subframe.
aaaand... you might as well replace your diff mounts at the same time because it's never going to be easier!

the koch tool makes it a breeze.
peter