I don't think you understand the definition of possible.No, you can't. Explain to me how you can achieve rapid directional input with an analog joystick anywhere near the frequency you can with a keyboard button? It's not possible.
Vibrate your hand by turning your wrist really quickly, sorta like picking a guitar string really fast. That's how to button mash really well also.
Edit:
Clubba re your prosthetic argument, Oscar Pistorius competed in the 2012 olympics. There are no rules against it.
The developers don't "Disable" the d-pad.So IMO you can't really compare them to something like a keyboard, which has a completely different form of input, which we know wasn't intended for ssb. If it was they wouldn't have disabled the d-pad.
All of the input is equal in the eyes of the CPU. It is just a string of 32 bits. Would it make you happier if you would be able to use the d-pad for smash? I can arrange it. Actually it is already done; the way my software works allows you to use whatever buttons you want to write that 32 bit string.