Image Sizes- Question

My old version of osCommerce allowed for three image sizes to be added on the product pages in Admin (small, medium, and large)...only the Medium would actually show up on the Product page. The small was for thumbnails throughout the site and the large was for the enlarged image from the product page. The width/height for each could be set in Admin-->Images.

How can this be done with MS2-MAX?? I would like a 100x100 small image for thumbnails (categories, featured products, etc.). Once a user clicks to the Product page, a larger 300x300 image would be displayed. Then you could click to enlarge to an even more detailed 600x600 image).

Under Admin--> Images there I only have the option to set the dimensions of a "small" image.

Any help would be appreciated!