Change session expiration after initialisation?

[eluser]AdamP[/eluser]
I have a problem with my authentification library. My work is based on this tutorial:

http://www.bramme.net/2008/07/auth-libra...-tutorial/

Everything works fine, but I would like to implement a "keep me logged in" function. That means that a session should not expire automaticaly after n minutes, but be alive for unlimited time (or set it to 1+ years).

This thread didn't help either: http://ellislab.com/forums/viewthread/114113/

Because at the time that a user logs in, the session is already set. The website is multilingual and the selected language is saved in a session. This is implemented with a pre_controller hook that set's the default language as soon as the website is loaded for the first time.

Is there a way to change the session exipration value?
Any help and solutions are welcome.

Adam