Well... I have no idea, really!
It may be not as easy to RE as it seems though. I wouldn't be surprised if it works like this:
- Nintendo created their own "cIOS" (except working with eShop purchases, obviously)
- This thing is kept not available to the rest of vWii
- It pulls the saves from regular vWii partition because why the hell not, but that's it
The pessimistic scenario is that they revamped whole IOS security system. Since they launched the thing without a global update, this doesn't seem probable.
The optimistic scenario is that this is already implemented in regular vWii IOSes , but this is even less probable.
Of course these are all guesses from
someone probably less educated than you.
Anyway, if this is what's happening and not some deep magic like a completely separate hardware mode, here's how GamePad access could work:
- The games and IOSes are changed to support this (special IOS GamePad API)
- Only IOSes are changed (repacking controls into Bluetooth packets)
- Only games are changed (special non-IOS GamePad API, like System Menu aspect ratio thing)
Anyway, in order to use this thing. Some people can decrypt Wii U HDDs or something, so it should be easily seen if they changed the games (...unless, like VC, there's a separate patch file, or unless their abilities don't work with the latest update). The cIOS changes, on the other hand, may end up being complicated to detect.
Alternatively, one could try to exploit an eShop Wii game. Whether this makes sense or not... depends on a game. Basically, the more complicated the save is, the more sense it makes. The currently announced games seem to be ones with uncomplicated saves - that said, that's what I'd think about Zelda, so well.
This all assumes that the CC > GamePad conversion is exclusive to eShop versions of games. If it's not (low chance, but who knows), this will simply work out of the box.