http://wiki.linuxquestions.org/wiki/...yboard_symbols
These will work in all X programs. Including Gnome and KDE(in theory... I am having issues with them right now myself, as per me trying to set up my multimedia keyboard. You can follow that thread in SuSE's section on these forums... I am hoping to find out more myself, as thus far only the AudioRaiseVol, LowerVol, and Mute work. 3 out of like 26 buttons...
But on gnome with metacity and gnome keybindings, it is suppoer to be much easier, however you will not have access to all the buttons in X, just Gnome...I am on KDE.