Thanks, just need some more help before trying it out.
1. What parameters are transferred by this hidden element
<input type="hidden" name="desc" id="desc" value="<?php echo $eCart1->TotalColumn("FullDetails") ?>" />
2. Would this be correct for the custom parameter for the ProductLongDesc
<input type="hidden" name="M_CustomVar6" id="M_CustomVar6" value="<?php echo((isset($_POST["ProductLongDesc"]))?$_POST["ProductLongDesc"]:"") ?>" />
The worldpay help documents describe a custom parameter as MC_ or CM_ whereas the confirm page uses M_C, does this matter and what is the difference between MC_ and CM_?
3. How do you add the loop that you describe?