$options = $Delivery->getConfig()->getOptions();
                $choices = $options['choices'];
                $choice_list = $options['choice_list']->getValues();★元のが見たい時はこれ(だったかな...)を使って
                $update_choice_list = array('xx' => 'xxxxx');★変更したいものを突っ込む
                $Shipping->remove('delivery');
                $Shipping->add('delivery', 'choice', array(
                        'choices' => $update_choice_list,
                        'required' => true,
                        'empty_value' => false,
                        'mapped' => false,
                    ));