I think it's had various inputs depending on the stage of his motor neurone disease.
Currently I think it tracks minor movements around his eyes or perhaps cheeks.
Ah yeah, probably
But what I was (badly) trying to say is
Does it need that input device? Or can it be adapted to anything?
This:
from the looks of it, you need to have a webcam so it can track your facial (mostly cheek) movements
answered that question tho