Bild custom opencart mod

I need a custom mod done on my opencart store , The Modification i need is to have some sort of product image layers , I have a list of colour options and t-shirt colour options , I need the Mod to change the t-shirt design colour whenever the specified colour option is selected , and also the t-shirt colour and style , As there is a list of over 20 t-shirt colours and about 15 print colours this will save me time in creating all the colour option images in photoshop. I have included an example website of what i am exactly wanting, You can find the link in the file i have uploaded , As you can see from the example website it loads 2 images . The first one T-shirt colour then a layer on top of that is the design image, I will also need a custom page made just like the example so when you get to the quantity box you click (enter personalization) and enter the text for each t-shirt quantity, If you look at the example website and select a product t-shirt you will see how it works. Please be sure you totally understand my needs before contacting me , Thank you