[Phil Richman]

Got it. Here is the final code if anyone else is interested in doing this.

<?php


namespace XLite\Module\Pmall\PmallSkin\Core;


abstract class Converter extends \XLite\Core\Converter implements \XLite\Base\IDecorator
{
    public static function buildCleanURL($target = '', $action = '', array $params = array())
    {
        $result = null;
        $urlParams = array();

        if ('product' === $target && empty($action) && !empty($params['product_id'])) {
            $product = \XLite\Core\Database::getRepo('\XLite\Model\Product')->find($params['product_id']);
            if (isset($product) && $product->getCleanURL()) {
                $urlParams[] = $product->getCleanURL() . '/';
                unset($params['product_id']);
            }
        }

        if (
            ('category' === $target && empty($action) && !empty($params['category_id']))
        ) {
            $category = \XLite\Core\Database::getRepo('\XLite\Model\Category')->find($params['category_id']);
            if (isset($category) && $category->getCleanURL()) {
                    $urlParams[] = $category->getCleanURL();
                    
                }
            }

            if (!empty($urlParams)) {
                unset($params['category_id']);
            }
        

        static::buildCleanURLHook($target, $action, $params, $urlParams);

        if (!empty($urlParams)) {
            unset($params['target']);
            $result = implode('/', array_reverse($urlParams));
            if (!empty($params)) {
                $result .= '?' . http_build_query($params);
            }
        }

        return $result;
    }
}