How to run this module on PHP4

The bot module uses the array_intersect_key() function only available in PHP 5 >= 5.1.0. If you're on PHP4, you can grab a PHP4 implementation of the function, written by Rod Byrnes 05-May-2007 09:10:

if (!function_exists('array_intersect_key'))
{
  function array_intersect_key($isec, $keys)
  {
    $argc = func_num_args();
    if ($argc > 2)
    {
      for ($i = 1; !empty($isec) && $i < $argc; $i++)
      {
        $arr = func_get_arg($i);
        foreach (array_keys($isec) as $key)
        {
          if (!isset($arr[$key]))
          {
            unset($isec[$key]);
          }
        }
      }
      return $isec;
    }
    else
    {
      $res = array();
      foreach (array_keys($isec) as $key)
      {
        if (isset($keys[$key]))
        {
          $res[$key] = $isec[$key];
        }
      }
      return $res;
    }
  }
}

Just paste that into bot_start.php at the top and you're good to go!