Very easy and you will not need a spring compressor. You do need one for the fronts.
You will need to remove the speaker shelf from the offending side to get easy access to the top of the mount. (The plastic bit that the seat belt routes through.)
Its a basic spanners, remove and refit job. I can do one side in 30 minutes, so it must be easy. It would be a good idea to replace both rears as a pair and also the foam or rubber insert that are fitted over the piston rod of the shock absorber.