Maybe you can get them working by getting the keycodes with xev and by creating a .Xmodmap file in your home directory.
Start xev from a console and type one of the keys -- does it display a keycode? If yes create a .Xmodmap file. Some sample lines of mine:
keycode 174 = XF86AudioLowerVolume
keycode 176 = XF86AudioRaiseVolume
keycode 160 = XF86AudioMute
keycode 222 = XF86PowerOff
Sorry, I don't know where I got the Names from (what is right of the "="), but Google is your friend if you need them.
EDIT: When using a graphical login manager I had to use .xprofile instead of .Xmodmap