I was actually heading down a similar path this past weekend regarding a Sitefinity RSS feed display control. Last night I wrote a blog post describing how I accomplished this:http://www.goondocks.com/blog/08-04-04/creating_an_rss_feed_usercontrol_in_sitefinity.aspx
Disregard my stupid comments at the beginning of the article, they aren't directed towards you. My girlfriend says I am incapable of writing anything without rambling for several paragraphs about nothing.
The control is very simple. There is a lot more I would like it do do (caching). I will probably continue to refine it.
In any event, hopefully this will help get you on the right path.