Thanks for the quick reply. I don't think I made myself clear. I want to replace the thumbnails in products.tpl, not product.tpl.
Here's an example:
I'm trying to get the detailed images from
http://www.puttinggreensturf.com/product.php?productid=16176&cat=252&page=2
to show up on
http://www.puttinggreensturf.com/home.php?cat=252&page=2
That's why I need some direction, it seems that there are going to be a few files for me to edit.