Late authentication

[August Karlstrom <fusionfile@gmail.com>]

I run Debian Wheezy with a simple window manager (Blackbox). If I 
remember correctly, in Ubuntu some applications like Synaptic and Update 
Manager ask for sudo password only when/if needed.

How do I configure the system so I can launch for instance Update 
Manager as normal user, check if there are any updates available and 
then provide the sudo password only if the system is to be updated? As 
Far as I understand the authentication is handled by Polkit.

Regards,
August