on *:TEXT:*.avoice on*:#: {
  { if (($nick isop $chan || $nick ishop $chan)) {
      set %autovoice. $+ $chan on
      msg $chan WHATEVER MESSAGE YOU WANT HERE  
    }
  }
}

on *:TEXT:*.avoice off*:#: {
  { if (($nick isop $chan || $nick ishop $chan)) {
      set %autovoice. $+ $chan off
      msg $chan WHATEVER MESSAGE YOU WANT HERE
    }
  }
}

on *:JOIN:#: {
  { if (%autovoice. [ $+ [ $chan ] ] == on) {
      mode $chan +v $nick } else {
      { if (%autovoice. [ $+ [ $chan ] ] == off) HALT }
    }
  }
}