This AFCi page says that they have lodged the appeal with both the FA and FIFA.

It's not quite clear what the grounds for appeal are supposed to be, beyond "Kanu is a key player for Arsenal and the Club does not wish to lose him for up to six weeks". But they do say that Kanu himself has "expressed his desire to stay and help the (Arsenal) team".

Perhaps he could just retire from International football. If he decided at a later date to "unretire", it would take a monumentally stupid Nigerian coach to turn him down.

Meanwhile, we've been told that Lauren has also been called up. Still looking for confirmation.