CAS Authentication with 2.7

I’ve installed the cas-authentication plugin with WP 2.7 and while I do get correctly routed to my CAS server for authentication, I am brought to the regular wp-login.php screen and get ‘incorrect password’ no matter what userid and password I enter.

Does a user need to log in to WP after CAS-ing into it?

I’m trying to get this up and running for a class tomorrow. Yipe!

Thanks in advance.