如何在Magento的结帐页面中获取所选的自定义选项值

I need to show the selected custom option in checkout onepage. I'm trying this, but it's not working:

<?php
$cart = Mage::getModel('checkout/cart')->getQuote();
$items = $cart->getAllItems();
?>

<?php foreach($items as $item): ?>

    <?php foreach($item->getProduct()->getOptions() as $o): ?>
        <?php foreach ($o->getValues() as $value): ?>
            <?php echo $value['title'] ?>
        <?php endforeach ?>
    <?php endforeach; ?>

<?php endforeach; ?>

This returns all custom options that I created. How to return only selected one by the customer?