Taking it as a carry-on may be the surest way to get it there, BUT even if it would fit in the overhead, will the airline allow you to take up that much room in the overhead? ... I know I have seen guitars carried on, even in 'hard' cases ...
also ... would putting the kb through the x-ray machine cause any problems for it? ... I know they put lap-tops through all the time, but ??? ... t.