Adding thumbs to checkbox list in cms

Hi

I have a section in my cms allowing the administrator to select a page layout. Currently this is set as a checkbox list. Each checkbox is identified as layout 1, layout 2 etc. I would like to enhance this list with a thumbnail wireframe of each layout so the user has a visual guide to aid his-her selection. 

Please could you point me in the right direction of where I would add a thumbnail to the cms. Suspect this may be a custom consulting job. Happy to pay if I need too :)

Thanks