Adding media keys

I have an older Mac Pro Keyboard (clear and white, one gen before the flat silver one) and I'd like to add the media key functions to F14-F16 on it that my flat silver keyboard at work has for iTunes control no matter which space I'm working in. However, I can't figure out how to do it. Is that just a function built into the newer keyboards, or can I enable it somehow on my older keyboard at home? Both my work tower and home tower are running the latest versions of Snow Leopard.

Thanks for the help!

 

I did, but with no luck. My changes didn't do anything. Also, there is nothing in that area on my work machine indicating what I should change on my personal machine.