I think what you probably want is a custom pipe. You can create a custom pull pipe with pass through to the publishing point. Using a pull pipe with pass through, you can display external data (such as an RSS feed) but don't persist the data in the database. This blog post has an example project attached that demonstrates what's involved in creating a custom pipe. Custom Pipe Example
. The example project isn't all that similar to what you're trying to do, but hopefully there's enough general info on custom pipe implementation for you to see if it would work for your needs and what would be involved.