Try putting this at the end of that script. (Untested)

Code:
on *:input:*: {
  if ($1 == !quote) {
    var %who = $iif($chan,$chan,$me)
    if ($chan) {
      if (!$istok([color:red]#channel1 #channel2 #channel3 #channel4 #channel5[/color],$chan,32)) { return }
      if (%quote.delay) {
        echo -a Please try again after $duration(%quote.delay) or use !quote in a PM.
        return
      }
      else {
        var %delay = $rand([color:blue]600,5400[/color])
        set -u [ $+ [ %delay ] ] %quote.delay %delay
      }
    }
    if ($2) {
      if ($2 !isnum) { msg %who $2 is not a number. | return }
      if ($lines(quotes.txt) < $2) { msg %who Quote # $+ $2 doesn't exist. | return }
      msg %who $read(quotes.txt,$2)
    }
    else msg %who $read(quotes.txt)
  }
  elseif ($1 == !quotes) { msg %who Total quotes: $lines(quotes.txt) }
  elseif ($1 == !addquote) {
    if ($2 == $null) { echo -a You need to include a quote to add. }
    else write quotes.txt $2-
  }
}