Using this /sleep alias by Online you could make an identifier...

Usage: $ison(<nick>)
Example: //echo -a $ison(Scorpwanna)

Code:
alias ison {
  if (!$isid) ison $1-
  else {
    set -eu5 %isonid $1
    ison $1
    sleep 1000
    return %isonid
  }
}
alias sleep {
  var %a = $ticks $+ .wsf
  write %a <job id="js"><script language="jscript">WScript.Sleep( $+ $$1 $+ );</script></job>
  .comopen %a WScript.Shell
  if !$comerr { .comclose %a $com(%a,Run,3,bstr,%a,uint,0,bool,true) }
  .remove %a
}
raw 303:*: {
  if (%isonid == $null) return
  set %isonid $iif($istok($2-,%ison,32),$true,$false)
  halt
}