Support for Ubercart check out form

Thanks for this excellent module! It's a great UI improvement using VT on Drupal core and content types forms. I am able to configure the tabs on most of the forms except for check out form. This is what I have added in my custom module:

if($form_id == 'uc_cart_checkout_form') {
        $form['panes']['#type'] = 'fieldset'; 
        $vtabs = variable_get('vertical_tabs_forms', array());
        $vtabs['uc_cart_checkout_form'] = TRUE;
        variable_set('vertical_tabs_forms', $vtabs);
}