I've found something very useful but I don't find any support

with this mod http://www.zen-cart.com/index.php?ma...oducts_id=1129

you are able to add files to you product it's working very well but to do this you must to create a new product type but I would like to add those new fields in a existing product type. And I don't know haw I can do this ?

Can you help me ?

thanks in advance.

Chris