Some nuggets I've found out about when investigating RSS and Atom authentication, which may be of use to you.
RSS (in all its flavours) uses HTTP Basic authentication, which is where you get a username and password dialog box appear in your browser when you try to access something.
Atom supports an extension to HTTP authentication.
If your corporate information system wants to use RSS then you're going to have to convert it's authentication mechanism, whatever that may be, to use one of those.
Microsoft won't support many forms of authentication in its RSS platform, but will
"support what's called NTLM/Kerberos pass-through authentication — which means that in many corporate environments where NTLM/Kerberos authentication is used (typically with Windows domains), the credentials that the user used to log into the machine will be automatically used".