It's possible, but keep in mind the product.tpl isn't for the faint of heart so back it up before playing with it.
Replace
Code:
{include file="product_thumbnail.tpl" productid=$product.productid image_x=$product.image_x image_y=$product.image_y product=$product.product tmbn_url=$product.tmbn_url}
With
Code:
{if $active_modules.Detailed_Product_Images ne ""} <font class=ProductDetailsTitle>
{include file="modules/Detailed_Product_Images/product_images.tpl"}{/if}
You'll see the above code further down on the product.tpl template too, remember to comment it out or you'll get a duplicate of the detail images.
Add that in the place of the thumbnail will use the detailed product images in it's place on customer/main/product.tpl.
If you only want the first image to show you're going to have to hack up product_images.tpl too.
The above should put you on the right track anyway.
Oh above examples are from 3.4.9 branch, not looked at it for 3.5.X but should be something similar