The only thing you can do is to install the printer via GPO startup script that runs before logon.
Wouldn't this also run in the context of an admin user, ie I'm thinking in the lines of how mapped drives do not populate properly when using a GPO script.
I doubt this would help for the unsigned drivers problem, but I've been working on a script to assist the GPO script with things like mapped drives and printers so that it runs in the context of the user. It's been tested some and so far it seems to work. If it's any use to you, I'd appreciate you commenting on it.
RunAsInteractiveUser / LaunchApp.wsf Conversion Testing
http://www.kixtart.org/forums/ubbthreads.php?ubb=showflat&Main=26830&Number=198514
