There are 2 issues. One is input broadcasting and the other is client modification. Neither are permitted. In general you should assume that any 3rd party technology that gives you an advantage over a player not using that technology is frowned upon if not outright banned. I’m not sure how you get multiple HUD displays in the same client without modification - maybe it’s possible, but I would submit a ticket to be sure.
A multiboxing tool that is OK can be found in the 3rd party developer section of the forum: