I was trying to play a flash game with my son that required lots of keyboard input. After a while my hard started to cramp and I looked for options to enable joystick support. I couldn't find a way to enable joystick support, and some Googling turned up that flash does not even support joysticks as input devices!?! I did find jkeys, which is a python wrapper to make your joystick emulate keyboard button presses. I made a tar file of the current svn release in case you can't get the code from svn. You'll need to yum install pygame to install a python libraries and then start jkeys as follows:
python jkeys config.xml firefox
Navigate to the appropriate flash game and you should be able to use your joystick with the buttons mapped to the corresponding keyboard keys. I recommend Robot Wants Fishy if you need a good joystick testing flash game.