Replacing the bushings can be a simple job, or one of the most unnerving experiences of your life. Having the proper tools is the deciding factor.
Here is a list of the minimum tools needed to complete the job (if you don't have these tools, or can't get access to them, I wouldn't recomend attempting the job)
Solid, level work aera.
Floor jack and minimum of 2 jack stands.
Grinder and a lot of grinding wheels (or my preference a cutting torch)
Wrench that will fit nut on radius arm
Hammer and Punch
Pry bar
13mm wrench
What you need to do first is remove the heads of the rivits that hold the brackets to the frame, then you need to knock out the remainder of the rivit. Once all the rivits are removed you'll need to remove the bolts that are still holding the bracket to the frame. Next remove the large nuts on the end of the radius arms, then the bushings and crossmember. Install new bushings and reverse removal steps. You will need to replace all the rivits you removed with bolts, tighten everything up and all thats left is to get it realigned.