So after a quick email to the Poqet PC mailing list, it turns out there's a sneaky little button hiding by the scroll lock. After you put in the batteries, you still need to poke the button with a pin to get it to turn on. Then it prompts you for a date. Woohoo! The thing's even Y2K compliant. Crazy.
But now I don't know how I can get new programs onto it, or data files off it. I'm pestering the mailing list for more information.