[kh99]

That looks like template newattachment - try adding it to newattachmentbit (although then you will get one per attachment and not one for the entire box).

If you want one that's not in the list of attchments but just has the id for the latest, it's a little harder, you'd probably have to create a plugin and query the database since the attachment info isn't saved after the list is created (or you could always edit newattachment.php).