rss/file.php needs to be improved to make it more generic, so that it uses "frankenstyle" component names.
eg mod_forum, blog, local_hub or gradeexport_csv
All you need to do is:
1) call get_component_directory($component) and get back a path, then look into that directory for rsslib.php and a standard function name and continue as before
2) make sure that the URLs point to this script with the correct component name.
3) test it again.