[gentoo-user] Trying to shutdown/reboot computer from gnome

[Damian]

Currently I cannot turn off the computer, nor reboot using gnome 2.28.2.
Googling around it seems that it is a polkit related problem. I've tried
to do what is mentioned here:
    
http://www.linuxquestions.org/questions/linux-mint-84/authentication-to-restart-and-turn-off-789357/

But polkit-auth --show-obtainable shows nothing.

I'm running gnome via startx, and the .xinitrc file looks like this:
    export XDG_MENU_PREFIX=gnome-
    exec ck-launch-session gnome-session

Could anybody manage to get this working?

Thanks in advance,
Damian.