I found the solution a few hours ago here http://en.gentoo-wiki.com/wiki/Systemd#PAM_support:_su.2C_sudo.2C_screen... . Now everything is fine :)
About the packages you mentioned, you've ran 'equery uses pambase polkit udisks upower', and none of them has the userflag systemd. Anyway, systemd is globally set on my system, and it is good to know I can disable consolekit. I'll try it right now. Thank you, -- João de Matos Linux User #461527
