In a word, IMPOSSIBLE. You put your votes in, the screen pops up with your choices, you doublecheck them. If no matter what you press, "Bush" comes up, then you should call the poll worker. But the vote won't be registered until you finish checking, then you press the red light. After the red light, you just see a screen, "Thank you for voting". So how could you register a wrong vote?
This is a total scam to try and convince those poor, deluded minorities the rich republicans are trying to steal votes. And they will believe it, just like they did last time, despite all evidence to the contrary.
What's funny is the old farts complaining about this will end up at the bingo hall later today playing 12 cards at once.