Custom template engine location

Before I go on to my question, let me give you a background of my project.

I have successfully made a custom templating engine for Drupal that is a port of Symfony2's Twig implementation and is located at /sites/default/engines/twig/twig.engine. My main reason for doing this is to take advantage of Symfony 2's Twig Translation extension that uses YAML for its translation table.

Now my problem is I am unable to get a path to my custom engine's directory. I would like to create an admin module that would allow me to modify the YAML files. The global $theme_engine returns NULL while drupal_get_path('theme_engine', '(twig|{my_theme_name})') is giving me an empty text.

Any help is greatly appreciated.

Thanks