Two things: First, not good at scripting really, need some guidance there. I know how to used rdesktop in terminal, but as far as creating a script, I'm a bit lost.
Second, this script would need to run automatically upon boot, and if the user fails to enter credentials in time, the script would loop, or give them the login screen again if necessarily. I suppose the script would also have to stop upon successful login. If the user gets kicked off their session, then somehow the script would have to be re-run. So I there, I think it starts to get a bit dicey.
Maybe building my own extension is the way to go after all.