If you get configurable products children custom attributes in Magento. then provided below code put that Code as per your requirements.
php
$_product = Mage::getModel('catalog/product')->load(108);//categoty id
$conf = Mage::getModel('catalog/product_type_configurable')->setProduct($_product);
$col = $conf->getUsedProductCollection()->addAttributeToSelect('*')->addFilterByRequiredOptions();
foreach($col as $simple_product){
var_dump($simple_product->getId());
}Share this playbook