Smashville

How do I bulk print an image on existing access cards? My company wants to add some internal contact info and such on the back of our existing cards. We are in the process of printing news cards for everyone this summer. Most are done. In the future, new cards would be pre-printed with this image, and when issued we would add the new hires info and pic to the front. I have enough experience to a simple access card, but not sure how to complete this task. Thanks,