It's not impossible. I'm currently learning it. It's incredibly difficult, and I think perfecting it will most likely take a lifetime -- literally -- but it isn't impossible. It is written for anybody with a normal amount of digits on their hands.
And by the way, just to add to the rest of the discussion, I have to say that Liszt's Transcendental Studies works were the toughest pieces I've ever learned (next to this one now).