I couldn't reply to a post below mine, which is why I replied to my own post.
The inline "reply" link doesn't show up until a while after a comment has been posted; but you can simply use the permalink for the comment, there you will always find a reply box.
Cheers!
Well, that's just a weird way to use HN.
At first read I actually thought he was arguing with himself ... Jeff Dunham, anyone?