You should be able to add more than one eCart object to the same site by clicking the add button and create a new eCart object with the different settings. But from there, you are going to add some custom cod to decide to which cart is going to be used. If you are going to use an select list, you might want to use a session which stores the user settings(language) and then set up your site using both eCart objects and use the session value to determine which cart to use.