I found this:
Thanks.
Could anyone possibly help? The name of the PHP file I need included is repchecker.PHPOk that addon has you manually add the template include to the message_user_info template. I suggest making use of the "message_user_info_avatar" template hook which is directly above where you would add that include. That way you can create your own template_hook listener and call that template with its own params.
Thanks.