The other dev of this project here - I think it's less of a challenge than presumed because, essentially, we're hijacking Facebook's markup structure anyway. All we have to do is inject stories one-by-one into existing elements rather than replacing the news feed entirely.

If you want this as an actual feature, create a new issue ticket for your request here: https://github.com/yczeng/hackernews-newsfeed. Happy hacking!