Eek, that I’m not sure of. You can see the code that pulls each of the form fields down, but it’s saving it at the bottom that does all the hard work. Adding your own fields is certainly possible of course, just add them to the template and save them after the product updates with the filters:
wcv_save_product
and
wcv_save_product_meta
Both actions here use the product ID as an argument so it knows where to save the data to for each product.