Mystile How to superpose an image over another one in the product gallery

Hi, I’m designing an e-commerce with Woocommerce and Mystile theme about Custom-made T-shirts, and I would like to save some time doing the next:

-Upload 6 images with different colors of the t-shirts
-Upload 6 images with differents styles of t-shirts
-Upload the logo of the respective t-shirt
-Apply the logo independent to the corresponding color or style of t-shirt

So in that way I don’t have to upload thousands of different images.

My idea is that in the product image there must be 2 images, the logo and the color or style of t-shirt, all must combinate automatically.

I think this can be done with z-index, but I have no idea how to apply at this plugin

http://wordpress.org/plugins/woocommerce/