I'm not an expert, but isn't manually scaling down all your images going to make them look like crap? And defeat the purpose of pixel art?
I'd just zoom in and learn to draw at lower resolutions. The computer will never be as good as you are at deciding which pixels are important, and which aren't.
I don't know why you'd want to draw at a higher resolution anyway; you're going to be doing twice as much work and ending with a product that looks half as good.
I'm surprised Pro Motion doesn't support larger tiles though....what if you're building a hi-res game? XP
Good luck finding a program if you still want to scale your stuff down, though. I just don't see why you'd ever do that, heheh.