We are currently in the process of refactoring the form types in a new - more generic - Sonata bundle, see https://github.com/sonata-project/SonataCoreBundle.
You might want to follow up on this repository for your dependencies.
However you are already able to use those custom form types, simply by calling them in your front end as you would in the back end. (For instance by setting the type to 'sonata_model_list').
Be sure that required CSS and JS are included in your templates (same as needed by the admin bundle currently).