At work I've written this jQuery plugin. It's only 2KB big and turns your normal radio buttons into images, you can set any images you like for src, checked and hover. Simply attach the configuration to your html input field as the class attribute as a JavaScript like object. I know you might want to attach a class to your radio buttons, but this is how far it currently is.

Here an example:

Get the JavaScript code
Get the HTML/JavaScript code

Edit: Just found this which seems to make this plugin obsolete. :-( Wish I would have found this earlier...