chachin, here you go:

on @$*:text:/^!(up|down)( |$)/iS:#:{ 
  var %m = q a o, %? = $regml(1)
  var %a = *!*@host1 *!*@host2 *!*@host3 *!*@host4
  if ($istok(%a,$wildsite,32)) {
    if ($$2 ison #) {
      mode # $+($iif(%? = up,+,-),$&
        $remove(%m,$chr(32))) $str($chr(32) $2,$&
        $numtok(%m,32)) | halt
    }
    .notice $qt($2) is not here!
  }
}

Replace !@host1, !@host2 etc...with the ones' actual hosts.