There is another way although it may be a bit unorthodox though its simple and effective. I used a cut to length 4x4 to span the gap between the top of the frame rail and the ceiling in the garage. I located the frame rail directly under a ceiling joist so the 4x4 post could be placed right on the joist. Had a helper steady the 4x4 while I used the jack under the control arm to raise it while compressing the spring. Before anyone says this method is unsafe, anything can be unsafe if common sense isn't applied.
Richard- I had to do the same thing- installing new springs in my bare frame. Use a good quality spring compressor- I borrowed a Snap-On model. You could use small pieces of rubber to protect the spring. I didn't use the rubber- I just went back after the fact and touched up the paint. Use a safety strap thru the spring and around the frame.
Not too bad an idea, With proper bracing of the 4x4 it would work. Thanks Randy, Ill probably wont sweat it then.