The rear shocks are held in place by just 3 bolts under the rear speakers, they are very easy to replace so I would recommend removing and the pressing old out and new in. You may be able to do it using a big hammer/small sledge but may risk damaging the shock in the process.
P.S. if the bushing is bad, I'm guessing the shock itself must be getting old too.
P.S. if the bushing is bad, I'm guessing the shock itself must be getting old too.