Access payment method in checkout end view

What do you mean by "access the payment method" ?

You want to know the payment method selected ?
For that you would have to load the order:
$app =& Jfactory::getApplication();
$class = hikashop_get('class.order');
$order = $class->get($app->getUserState( HIKASHOP_COMPONENT.'.order_id'));
echo $order->order_payment_method;

It's possible.

In that case you need to do like that:

$app =& Jfactory::getApplication();
$class = hikashop_get('class.order');
$order = $class->get($app->getUserState( HIKASHOP_COMPONENT.'.order_id'));
$paymentClass = hikashop_get('class.payment');
$payment = $paymentClass->get($order->order_payment_id);
echo $payment->payment_name;