You don't need a dll, you might need to tweak this a little, but this is the basic idea.
Code:
on *:filesent:*:{
  if $send($nick).cps > $gettok(%record.CPS.sent,1,32) || !%record.CPS.sent {
    set %record.CPS.sent $send($nick).cps $nick
  }
}
on *:filercvd:*:{
  if $get($nick).cps > $gettok(%record.CPS.rcvd,1,32) || !%record.CPS.rcvd {
    set %record.CPS.rcvd $get($nick).cps $nick
  }
}
alias recordcps {
  if %record.cps. [ $+ [ $1 ] ] {
    tokenize 32 $ifmatch
    return $2 ( $+ $bytes($1).suf $+ /s)
  }
  return n/a (n/a)
}
to display it, use $recordcps(sent) or $recordcps(rcvd)

//echo -a DCC Highest Send Record by $recordcps(sent)
//echo -a DCC Highest Recieved Record by $recordcps(rcvd)