How to implement IAP in Win/WP 8?

Is there a resource in the documentation or maybe an article on getting started with IAP in Windows 8? I was reading through the documentation but the only thing I found was this page and it was specifically for iOS. I was thinking maybe we're supposed to implement the IAP inside visual studio when we export our project but I'm only guessing. Actually come to think of it I can't find anything on IAP for any platforms except for the page I mentioned before. Any suggestions?