gistfile1.py

class CustomModelManager(models.Manager):
    _connection = None

    def get_query_set(self):
        return QuerySet(self.model, self.create_query())

    def create_query(self):
        return Query(self.model, self.get_connection())

    def get_connection(self):
        if self._connection is None:
            if hasattr('settings', 'CUSTOM_DATABASE'):
                self._connection = self.create_custom_db()
            else:
                self._connection = connection
        return self._connection

    def create_custom_db(self):
        database_conf = settings.CUSTOM_DATABASE
        to_import = 'django.db.backends.' + database_conf['DATABASE_ENGINE'] + '.base'
        backend = __import__(to_import, {}, {}, ['base'])
        return backend.DatabaseWrapper(database_conf)