Swap image on mouse over in category view

[ar58]

hi can anyone help me what to change in the code for making a swap main image product on mouse over in category view to the second image

for example, I add a template that has the feature

http://joomla.vinagecko.net/t/vina_rossi/en/virtuemart/shop-pages/front-page/basketball


can someone guide me how to do that to which files of php to override and what css to make for it.


thanks

[GJC Web Design]

Its not a VM question .. its a coding question

the file will be the sublayout products.php