How do I adapt this quiz-answering script to this new quiz layout?

I want the browser to be able to select correct answers to questions. I found an answer that seems to be the right idea (How can I automatically select specific radio buttons with Greasemonkey?) but I don't know enough javascript to use it.

My HTML code is shown in but i can't adapt it like as follows
http://jsfiddle.net/66Lam/

Ex: it's working here, but i can't adapt it my code.
http://jsfiddle.net/kDThC/8/

Can you adapt it for me Please ? THANKS GUYS