Zeuscart/Opencart digital product download link modification

We have a plain site now. We would like to upgrade to a shopping cart, preferably Zeuscart and opencart is our second choice. We have DRM'd pdf books in our site. The DRM company requires to follow a certain URL (link) for the product download to work with the DRM. The basic requirement is after the products are added to the cart and checkout, the customers will pay for all the products at once thru different payment options like paypal or credit cards or third party payment system. After the payment is successful, the user is mailed links to download. The links should be in the following format: [login to view URL] where #productcode# is the product's unique code and #usermail# is the buyer's email address. This project was posted earlier, but most of the bidder's didn't understand the problem, hence, the repost. I've an example from the DRM company for OSCommerce, which could be helpful.