Comment 5 for bug 1094278

for what it's worth: i suspected this is restricted by pam's capabilities.

so i added a line to /etc/security/group.conf:
cu;*;ummelum;Al0000-2400;dialout

and created /etc/pam.d/cu:
session optional pam_permit.so

i used a login-shell and tried my serial console, but alas...

if i try with pkexec, from a login-shell, i get the following in /var/log/auth.log:
Dec 1 23:49:02 iugo polkitd(authority=local): Unregistered Authentication Agent for unix-process:914:1133 (system bus name :1.73, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)

but, i don't think my pam-configuration is correct.