So, I managed to do this which to me was pretty cool since I did a dair by accident and I still managed to get really high, notice I still had the second jump at the end of the tornado:
(in case you can't see the embedded gif
http://gfycat.com/PerfectQueasyFlies )
I did this my sliding my fingernail on the b button instead of mashing, I can change the position of my hand pretty quickly from a standard grip to this but I still have to practice to get it more consistent, I have no trouble if I'm expecting to do a tornado but if I do it by accident well...not cool haha
Edit: I should probably upload the video since it sounds as if I'm pressing the button 1000 times a second

this was done on a gamecube controller by the way but I have no problem doing it with any of the others, I've been doing this kind of mashing since that tiny toones olympics game on the snes