Disclaimer: I hold no responsibility for any damage to anything related to everything lol.
I've seen someone say they used VERY heavy duty zip ties but i dont know if thats such a good idea. Why cant you leave the compressor in it? If its internal the rod should be able to pull right out of the hole in the control arm (up front). Maybe you could use a few smaller chains and master locks or something, but i think its a better idea just to use an internal compressor and remove it through the control arm up front. Or you could do what the above post mentioned but be VERY careful either way. Those suckers pack a punch.
In the rear: Its easy. You dont need a compressor. You can do this a couple ways. Place jack under differencial. Jack up car. Support on jack stands (support not only axle but body also, you'll see why if you dont, it leans like crazy when you let one side down). While one side is up as high as it can (the axle) let the other side down all the way. Be careful to observe tension on brake lines etc. Make sure it is all the way decompressed. Remove. Replace, jack up and repeat.
The other way, which i think is just as easy, ESPECIALLY if you're chaning the lower control arm also, jack up the rear, support the rear. Support the car. Place jack under lower control arm. Remove tension from bolt attaching it to the axle. Remove bolt. Slowly lower arm. Remove Coil, then install it in reverse way.
Whatever you do just be careful, take your time, and geterdone. It took me forever to install the suspension in my sig (just finished this morning) but its finally done and it was worth the wait and effort.
-GM