It's actually a pretty straightforward procedure. Here's what you gotta do:
1. Tear away the trunk or hatch sidewall carpeting and expose the top shock mount brackets.
2. Use a pair of pliers to hold the piston while removing the nut.
3. Using an impact wrench is most effective, but the lower shock bolt can possibly be removed with an 18mm box end on one side and 15mm socket and breaker bar on the other.
4. Remove the shock and stop, install new shock and stop and reattach the bolts. Attach the lower bolt loosely; final tightening must be done while the vehicle is on the ground.