Add the following lines of code to your loader file
$loader = new Phalcon\Loader();
$loader->registerNamespaces([
'Phalcon' => '/path/to/your/vendor/phalcon/incubator/Library/Phalcon/',
// any other namespaces you have loaded
// ...
]);
$loader->register();
Now you can access all the Incubator functionalities by using the normal Phalcon namespaces:
\Phalcon\Acl\Adapter\Database;