Help needed to install ac wifi card for late 2012 retina mbp.

So hey guys, i was reading a thread here on ifixit about how the wifi card is exactly the same between the late 2012 13 inch model and late 2013 one. People were saying how they replaced it and all that. But i would like to do it, the thing is just that i am not sure how and am afraid of breaking it. Also someone wrote that the card he bought had a thermal insulator missing so that could damage te motherboard. How true is that and which card model should i order? Thanks in advance.