Is it possible to programmatically register a custom entity type as an Organic Groups group? I know I can add a group field to the entity type using the UI, but I would like to register the entity type as a group in the module code. Users should be able to add such an entity and then these entities should automatically be a group and the checkbox should be hidden from the administration form.
Of course I could 'check' the checkbox and hide it by altering $form and $form_state, but I feel it is a better practice to register it as group in the entity type definition, if possible at all.