who-ing is sufficient; next time at least try your own smile
Code:
alias nonregistered {
  if ($me ison #$1) {
    ; enable group to grab raw replies
    .enable #nonregistered
    ; secure disable of that group
    .timernonregistered 1 30 .disable #nonregistered
    ; store channel to check
    set -e %nonregisteredchan #$1
    ; request users list
    who #$1
    ; create hidden sorted list window for that chans nonregistered users (or hide&clear existing window)
    if ($window($+(@,nonregistered,$chr(160),#$1))) { window -h $v1 | clear $v1 }
    else { window -hlsCk0z $+(@,nonregistered,$chr(160),#$1) -1 -1 300 500 }
  }
  else { echo -a Syntax: /nonregistered <channel>. You have to be on that channel. }
}

#nonregistered off
; who replies
raw 352:*: { 
  if ($2 == %nonregisteredchan) {
    ; add nonregistered nicks to the hidden listwindow
    if (r !isincs $7) { aline $+(@,nonregistered,$chr(160),$2) $6 }
    haltdef
  }
}

; end of who
raw 315:*: {
  if ($2 == %nonregisteredchan) {
    ; show the formerly hidden window, unset stored channel, execute "secure disable"
    window -a $+(@,nonregistered,$chr(160),$2)
    unset %nonregisteredchan
    .timernonregistered -e
    haltdef
  }
}
#nonregistered end