if windows authentication is useed rather than enterprise it can be done with out a click.
Logon.csp, and I think from memory you pass "" as user name "" as password and the authentication as sec_WindowsNT. The user would not need to touch the keyboard, you just open the page, it logons and redirects on succesfull logon or on failure rediredct to logonform.csp
Regards.
Mark.