Modify Custom Magento Theme to work with Zetaprint Extension

We have installed Zetaprint Web to Print Extension on our custom theme. It's not working the way it should so we need it to be fixed. We need to modify it so when a visitor lands on the product page.... the original product image shows up and when they click preview personalization the original image will be swapped with the preview image. This is the default behavior of Zetaprint but our custom theme is not working correctly with it. We will also need some other modifications with the Zetaprint system so anyone who has worked with it before is preferred. The custom theme we are using is called Legenda [login to view URL]