How to Use Supporter with Market Press to create a marketplace?

I hope to use the Product Theme, and perhaps some others, in combination with the Market Press plugin to create a marketplace where local small businesses can pay to have their own sites/stores. I thought that Supporter would be the way for me to charge the businesses for setting up their stores.

After reading the Supporter documentation, if I understood it correctly, only the 100 Theme pack, Dixie, Triten, and Nelo contain the necessary coding. Use of any other theme would require modification of the theme. I would like to use Studio and Product themes. I did not understand how to modify those themes to use them with supporter. The Supporter documentation gave some examples of the necessary code but I don’t understand where to put it.

Maybe there is a better way for me to accomplish my objective. Help?