First, USE A SAFETY CHAIN!
Second, if you loosen the bolts for the FCA to K-member, you can then likely pull the FCA down low enough for the spring to come out.
Note: People have been killed by springs flying out!
Just because someone says it's okay, that is
not true!
Many idiots drink and drive and text and drive. Also, many of those idiots DIE!
Do not be foolish! If you do the lowering FCA and prying spring out method, then spend a MASSIVE ~$10 at Wal-mart, get a chain and some bolts, loop the chain through the k-frame and FCA, tie the ends together with a bolt and nut, and drop the FCA/spring.
BTW, for sn95's the springs do just come right out by hand.
But, that's with a different (longer) FCA and different k-frame.
If you do want to know what the correct spring compressor tool is, and how to use it, see:
http://www.veryuseful.com/mustang/tech/tmp/OTC-spring-tool/
Good Luck!