try this for starters. If you don't want it muted from also showing the notice where it "belongs" then delete the "haltdef".

Code:
ON &^*:NOTICE:*:*:{
  if (!$window(@notices)) window -ez @notices
  aline -hp $color(notice) @notices $asctime([HH:nn:ss]) $nick -> $target $+ $network $+ : $1-
  haltdef
}