Integration with twig template engine

[reidsneo]

How do I integrated PIP with twig?
I want to replace current render() view with twig render
just by calling $template = $this->loadTemplate('index.html');

instead calling
$loader = new Twig_Loader_Filesystem(ROOT_DIR .'application/views/');
$twig = new Twig_Environment($loader);
$template = $twig->loadTemplate('index.html');

Thanks