I'm afraid that in looking into the more complicated solution, you've overlooked some great resources that are already available to use with much less setup.  The best program for multimedia keyboards in linux is called "keyTouch" and is available at http://keytouch.sourceforge.net/.

 An older program (development seems to have stopped about five months ago) is LinEAK, available at http://lineak.sourceforge.net/.

Both of these programs require the user to simply select the keyboard and their multimedia buttons work with no more configuration.  keyTouch allows the user to add or change the commands, all without delving into the command line.

 Respectfully,

Jacob