Get a configurable product's children with custom attributes attached...

Magento_Test.php

<?php
$configurable = Mage::getModel('catalog/product_type_configurable')->setProduct($_product);
$collection = $configurable->getUsedProductCollection();
$collection->addAttributeToSelect('*');
$collection->addFilterByRequiredOptions();

foreach ($collection as $product) {
    print_r($product->debug());
}