If you don't have a pickle fork, or it's not working for you (it didn't for me) then you can thread the nut down onto the ball joint, then beat the shit outta that nut with a 3lb sledgehammer. Beware, you'll need a new spindle nut, and don't thread the nut down so far that the hammer comes into contact with ball joint. (unless you don't care about your ball joints)
Paul.