Idea for a Movable Type plugin

I want to let people in comments refer to other comments, and then have the plug-in auto-link to those comments. The idea would be to let people say:

In comment16, Rick said…

The plug-in would look for strings that say “commentxxx” where xxx is the number assigned to the comment, and then auto-link the string to the permalink for the comment. End result? A way of linking related comments without actually threading the discussion.

I can assign permalinks to comments. I don’t know how to parse text and modify the resulting HTML… Anyone care to lend a hand?