$app = new Glue\App;

$app->config->override([
    'twig' => [
        'path'    => '/absolute/path/to/templates/folder',
        'config'  => [
            // Additional Twig config, read Twigs 
            // documentation for more info...
        ]
    ],
]);

$app->register(
    new Glue\Twig\ServiceProvider()
);

$twig = $app->make('Twig_Environment');

$twig = $app->twig;