What hooks should I use to parse a post?

[UltraVR]

I'm trying to write a plug-in that takes a user's post, parses it, and replaces certain phrases with links.

The script works independently, I just can't figure out which hooks to use to make it work with vBulletin.

This is the way it works: A function is called, it parses the text, and then returns it back to the original variable.

Anyone have any idea where to put the function and the $messagetext = functionname($messagetext); line?

(Sorry for being so retarded)

Thanks!

EDIT
Nevermind, I got it. Delete this.