$conf = Mage::getModel('catalog/product_type_configurable')->setProduct($currentProduct);
    $childProducts = $conf->getUsedProductCollection()
    ->addAttributeToSelect('id')
    ->addAttributeToSelect('size')
    ->addAttributeToSelect('color')
    ->addAttributeToSelect('millship')
    ->addAttributeToSelect('closeout')
    ->addAttributeToSelect('msrp')
    ->addAttributeToSelect('price')
    ->addAttributeToSelect('soldby_caseqty')
    ->addAttributeToSelect('case_qty')
    ->addAttributeToSort('size_value')
    ->addAttributeToSort('color_value')
    ->joinField(
        'qty',
        'cataloginventory/stock_item',
        'qty',
        'product_id=entity_id',
        '{{table}}.stock_id=1',
        'left'
    );