The proper way is to use a jaw type gear puller. The ghetto way is easier...
1) Jack up the front end so that the wheels hang free, put jackstands under the frame.
2) Take the covers off from the bottom of the torsion keys and remove the torsion bolt.
3) Use a bottle jack on a cinder block or wood block (for height) and lift the end of the torsion key a little bit.
4) Now you can slide out the tab of metal that that the torsion bolt goes through.
5) After removing that tab, slowly lower the bottle jack and allow the torsion key to rotate down.
6) All the load is now off the bar, you can slide it out of the lower control arm.
You can save the cost of the new keys by flipping the torsion key over and grinding a divot for the bolt to rest in. Do a search for torsion flip over on ExplorerForum.com, I seem to remember a pretty good writeup over there on it.