If 4.2 is the same as the 4.1 branch, in product.tpl, the variable $cat contains the categoryid of the current product, so you could do if-than statements based on the $cat variable.
You can test by temporarily putting this code in product.tpl and see if it gives you the data:
Code:
<br />category: {$cat}<br />
If it works, you can use if/than/else statements based on the $cat variable to make the page.
If you need differences for other category pages, you can try the solution posted
here.