Borrow or rent a spring compressor. The jack will keep the spring in place, but when you let off the jack to get it out, it can come flying out, and can be really dangerous. Putting springs back in without a compressor can be a lot of fun too.

The compressors are basically just threaded rods with a couple of hooks to capture the coils.

http://www.classicperform.com/produc...sor-single.htm