Apple wireless BT keyboard: how to enable those special keys?

[Jurgen Kramer]

The Apple bluetooth keyboard works just beautifully with Fedora and the
hidd daemon. Most keys work but unfortunately some of the special keys
don't even seem to emit a key code (tested with xev). 

The keys F13-F16 and Volume up, Volume down, mute and eject do not work.
I modified the XkbModel in xorg.conf to "power_g5" and tried xmodmap as
suggested on the net but no go.

Any idea how can I enable those extra keys?

Thanks,
Jurgen