BDN - Banner Developer Network

Hi All,
I am trying to create a portlet that would SSO to Banner SSB application. Right now the Banner SSP app is a blackbox. I can't control it. I was not successful in doing SSO by simply supplying userId and the password to the URI /prod2/twbkwbis.P_ValLogin as I am getting a 401 error while submitting the form. It seems like I am missing a header. I really can't see the header as the app is exposed via https. Need help here from the experts.

Thanks,
Amar.