[eluser]OverZealous[/eluser] @NachoF
DMZ's examples include a fully-functional authentication setup. For me, authorization is application-specific, and I do not use any off-the-shelf libraries for it.
I use a simple User belongs to a Group setup, with each group having a series of flags enabling or disabling functionality. I also extended CI's Session library to provide convenient methods for checking access (e.g., $this->system->can_view('action')).
Sorry I cannot be of more service than that. I tend to write my own tools most of the time, because it's often difficult to shoehorn someone else's code into my app. (Irony intended ;-))