Hi,
It should be possible. Create a custom field of the table "product" via the menu Display>Custom fields with the column name "product_addtocart_message" and the type "text".
Then, in each product, you can fill in that custom field with the text you want for the add to cart button.
This will be used on the products listings if that product is displayed on listings and you activate the display of the add to cart buttons on the listings, on the product details page and also for the add to cart button you can display with a content tag.