A spring under compression is a restrained force and carries a danger. Always be careful. Its all fun and games until someone loses a finger..... You are officially warned.
I took my struts apart with an impact electric driver. You take the strut off of the car, intact, and lay it on its side on the ground. Put a foot on top of the spring and, with the impact tool, knock the big nut off. It'll spring apart with a little force. I kept my fingers (toes, etc) out of the way.
The new springs are shorter and will be easy to install.
The rears just come out when the rear beam gets drooped.
Look up my Bilstein coilover install thread where I covered some of this (with photos).
John
P.S. I have never done it but I have been told that people have used hose clamps to restrain the springs.