“They want a user to be able to decide when to listen to the director” Case is just reverse; director want to be able to decide when to listen users,
AnswerThere are many solutions to this :  Here is one simple way  On every panel make -      separate LISTEN key to director -      separate TALK key to Director  in ECS card / ports (hardware setup ) select directorpanel port in the advance settings for the director panel -      set Eavesdropping to be TRUE -      Set Audio presence tally to be true . This method means that users can decide to listen to director bypressing their Listen key And talk back directly to the director.