$node = Mage::getConfig()->getNode('maxcache/cache/type');

        Zend_Debug::dump($node);

        $parentNode = Mage::getConfig()->getNode('maxcache/cache');

        Zend_Debug::dump($parentNode);

//change child named 'type' value to be test

        $parentNode->setNode('type','test',true);

        Zend_Debug::dump($parentNode);

        $node2 = Mage::getConfig()->getNode('maxcache/cache/type');
        Zend_Debug::dump($node2);