Shopping Cart Item URL's

Hi Everyone - I am running zencart 1.3.8 and I have what i think is an interesting usability question.

My store sells music and along with physical cd's, we are going to offer digital downloads. A user can buy a full album or individual songs.

I have set the store up so that each individual mp3 item is hidden (an active directory inside an inactive directory). The only place I want the customer to be able to add individual songs to their cart is via the product page for the full digital album. To achieve this, I have manually inserted the add to cart buttons for each individual song item in the HTML of the full album page.

The problem I am facing is that once a customer adds an individual song to their cart, if they click on the song link in the cart, they are directed to the individual mp3's product page (where I don't want customers going).

What I would like is for clicks on the individual mp3 links via the shopping cart to go back to the full album product page.

An example of this functionality working is at my friends store here: http://www.fixtstore.com/product/3537/iammynewt-vs-Skullduggery---Ohaka-(MP3-Album)

If you add an mp3 to cart, and then click on that mp3 item in the cart, you will be taken back to the full album page - and not the individual mp3 page.

So anyone have any thoughts or ideas?

Thanks for taking the time to give my post a read!