PS3 + Featured Pod / Popular Pod

Can someone please explain how product selection works in the ‘Featured Pod’ (left pod) on the home page? I’ll really appreciate someone explaining this to me.

I understand that the basis for the product selected to appear in the ‘Popular Pod’ is the product with the highest number of sales. This would be OK for most businesses but I sell collectible books. Therefore, I very rarely have more than one of any particular item for sale and once a book is sold, it’s out of stock. So, in theory, there would never be a most popular product and if one appeared in this pod, it would be out of stock.

I therefore need a way to change the contents of the Popular pod manually so that I can use it to feature new books as they arrive. I’m comfortable with the css needed to do this but don’t want to cause any conflict within the php parts of the programme by deleting code willy-nilly. Any help with this problem will be very welcome. Thanks in advance.