Thread:Extension talk:ConfirmEdit/How do I edit the help message?

I found the message given on the login screen, at ConfirmEdit.i18n.php and edited it to mention the Asirra cat puzzle that I'm using (by default it talks about a simple math problem). Now how do I edit Special:Captcha/help ? Even using the full address and adding on &action=edit wouldn't let me edit that page.