How to add number of comments as a clickable link to an rss feed?

I need to be able to read the rss from one site and have it spit out the title, excerpt, date, and number of comments as a clickable link. I would prefer not to hack the built-in rss feeds. I could probably do this with creating a page template and page masked as a custom feed but I just want to see if there is a better / cleaner way of doing this.