alias masshl {
  var %x, %y 1
  while ($nick(#,%y)) { 
    if ($v1 != $me) { 
      %x = %x $v1 
    }
    inc %y
  }
  msg # $v1 %x $+ : $$1-
}

You have to be sure the $1 is entered by adding an extra dollar sign, or else you'll get all the nicks without the message.