If you get nolothane type bushes, they come in two pieces so they just push in by hand.The old bush, if its original will sometimes need to be cut out with a knife.Ive ran into a few like this now that Ive had to cut out to replace them.Its not hard to do though.
Its fairly straightforward, jack up the rear of your car and place it on stands. Next, undo the retaining bolt at each end and pull or pry the panhard rod free from the vehicle. Next step is to press out the old bushes using a hydraulic press, alternativley you can press them out using a bench vice and a socket of the same diamater (or slightly smaller) as the bush. From here on the proceedure to fit new bushes is the reverse of removal. Remember to grease up the new bush before attempting to press it in.
The grease serves two purposes, firstly it makes pressing the bushes in a shitload easier. Secondly it stops the new bushes from creaking and squeaking as certain loads and forces act upon the suspension.
Dishwashing liquid/liquid soap is preferable to grease though as it will wash away after installation and not interfere with the way the bushes are meant to work. You can install them dry but it's a bit more difficult.
Just did mine the other week. I pressed the old ones out, but cutting them would work. I replaced them with single piece press in superpro bushes. Just greased them up with the grease provided, and with one good smack with the hammer, they fell in!