355 rear shock removal questions

One of the rear shocks in my '98 355 is leaking a bit at the top and the suspension does not feel like it should, not to mention that it is getting pretty squeeky to the point of embarrassment. I want to take off both rear shocks and have them rebuilt. How involved is the removal and reinstallation? Also, does the back of the car need support the whole time the shocks are out or can I just put the wheels back on and remove the supports? I did a search and saw that some DIYers have removed/replaced the shocks but never really said how involved it was.