You don't even need a compressor for the W124 rear springs...just 2 jacks, one under the control arm, the other holding the car up. Undo the bolts for the shocks, swaybar etc. and slowly let the control arm down...the spring will just slide out easy. Jack the arm back up, line up all the stuff and re-bolt.
Fronts are almost as easy with the Klann tool...don't need to take anything apart, just jack car way up and fully compress the spring with the tool and remove.
I couldn't believe how easy it really was.