What Ellman02 described with the third party program is bannable. Don't do that, and if you've been doing that, I'd suggest stopping now that I'm back from the holidays.
As far as using in-game hotbuttons to remind your second box that the hotbutton has completed, that's fine. Just make sure you're keeping an eye on that second window when you get that tell. If you were to receive an automated unattended macroing test or a manual check from me personally... and then you didn't check the screen (for reasons including but not limited to being mezzed on your other character or going to the bathroom IRL), then you'd be guilty of unattended macroing.
Make sure you keep an eye on that screen. The use of a multi-cast hotbutton is convenient, but the intent is that you aren't just doing something else and letting a program do everyting for you without you babysitting it.