The only way I can see to do it is constantly scraping HN's pages(unless there's an API?). On another note, having source code on your screen randomly shift and change large blocks of itself might be suspicious, defeating the purpose of this.
He was joking about the comment "//why isn't this async?" which appears in every entry.
Oh, I seem to have missed that.
There is not an official API. However, there is a partially complete API available from the guy who made iHackerNews at http://api.ihackernews.com/ -- it works well, but stuff like voting is disabled.