Adding functionality to specific locations on WooCommerce is fairly easy to do. With a little bit of planning and learning about Hooks and how to add them to config.php, you can do a lot. I recently needed to add a message to cart to tell users in Canada that in order to purchase, they can use a Canada billing address but MUST use a US shipping address. Hooks to the rescue!
Here are a couple links describing hooks and how to use them.
This link defines all the places you can use a hook.