Just say that you are playing several accounts with a shared broadcasted keyboard. If this is done by software or hardware doesnt really matter, so I dont really mention it unless someone asks.

If you read through ToS and EULA you will see it is only illegal to use software that automates things, mines data or makes decisions.

Im using the multibox application to broadcast my keyinputs. I cant really see how this is different from any other remote tools like vnc or such.