@WRDSB,
Im sorry HTTP authentication isn't available. It's actually a Wordpress core issue, because the RSS library used doesn't support it.
The Dashboard Feeds plugin uses the "fetch_feed" Wordpress function. That function runs off the SimplePie library, which currently doesn't support http authentication.
With custom coding, you could use the Wordpress HTTP API to retrieve the information. This way you could add headers for the http authentication. However, at this point you'd also need to implement your own RSS parser.
Thanks for being a WPMU DEV member. Let us know if we can be of any further assistance.
Best regards,
