Don't know if there already has a solution for this or not, but you can get it by making a template override
(Understanding about VIEW in VM 2:
http://forum.virtuemart.net/index.php?topic=90935.0)
- First, find the code to control "categories" layout here:
/components/com_virtuemart/views/categories/tmpl/default.php
- Then, read code of generate add to cart control, in product details view:
/com_virtuemart/views/productdetails/tmpl/default.php
and
/com_virtuemart/views/productdetails/tmpl/default_addtocart.php
Then you can easy bring the add to cart function to categories view.
I know that this is a hand-by-hand guide, but I hope that it will give you a point to do a research and then apply it for your own purpose
