RSS feeds with authentication

I have a site that requires people to login to see their personal
notes. Others can share notes with them, and comments on their
notes. I’ve created an rss that gives you all the changes that you
haven’t yet seen.

My question: How do I log the user in the get the rss feed?
Remember, the feed is specific to each user.

Can rails do this? What is involved? My authentication model is just
a simple salt/md5 and storing the user in the session. But obviously
I can setup this one action to by pass that and use different