The differencial bushings were a bear of a job. It was discussed recently by another member in very good detail. Warning: It is work intensive for a DIY'er, even with the right tools, but not impossible since I did it.
The inner bushings are completly different from the outer bushings. However, they both have metal outside and they DO have to be pressed in or pulled in. There is a special tool to do it and, it is fairly simple once you figure how to use it.
You have to disconnect the rear sway bar links, the shocks, springs, and the lower control arm, of course.
You may want to do this if you are going to replace shocks, springs or the sway bar links since you already half way there.
My inner bushings were in good shape. Are you sure the squeeking is from the inner bushings and not the outer bushings or the sway bar bushings?
The symptoms I had was squeeking when I got in/out of the car. Loose feeling when going thru a small bump and/or slow speed braking.
I hope this helps!