public static function executeTask($class_name, $arguments = array(),$options = array())
  {
    $dispatcher = sfContext::getInstance()->getEventDispatcher();
    $formatter = new sfFormatter();
    $task = new $class_name($dispatcher, $formatter);
    chdir(sfConfig::get('sf_root_dir'));
    $task->run($arguments, $options);
  }

und den Cache dann zB so löschen:

  public static function clearCache()
  {
    $class_name = "sfCacheClearTask";
    self::executeTask($class_name);
  } 

[code: Dheeraj Kumar Aggarwal, via googleGroups]