hmmm, the ordering system that Mongoose use looks like it takes voucher codes.
I wonder if it is smart enough to apply an offer to a specific deal, or if it only takes straight discounts (or discounts on orders over X currency units).
Still, that said, it might always be possible to Mongoose to add another product page, with a URL you can only find out from S&P, which then lets you order "X and Y Monty Offer Pack" or so on.
... OK ... I must stop creating work for the lovely people at MT now.