public function registerEntityClassesMetadataDriver(Array $classes = array(), $namespace = 'Psc', \Doctrine\Common\Annotations\Reader $reader = NULL) {
    if (!isset($this->entityClassesMetadataDriver)) {
      if (!isset($reader)) {
        $reader = $this->createAnnotationReader();
      }
      $this->entityClassesMetadataDriver = new \Psc\Doctrine\MetadataDriver($reader, NULL, $classes);
      $this->registerMetadataDriver($this->entityClassesMetadataDriver, $namespace);
    }
    
    return $this;
  }