Geeklog, and UNIX user accounts?

How difficult would it be to have GL set up, so when a person creates a new user account, it creates a *nix account on the machine itself?

Or something to that extent, as i run free email services from my machine, and all my email users are actuall accounts on the machine, and i would like people to be able to create accounts freely from the website, prefferably from the GL user creation page, then they could begin using their email services immediately, instead of myself having to create the unix accounts myself