nevermind...after playing a little I realize you need to use the arrow keys to move to the next spot anyway so it doesnt matter if you have across or down highlighted when using the keyboard.
I can't believe they couldn't come up with a decent control scheme considering that is the main gameplay element to this. It is sad. I heard the messenger kit doesn't even work correctly, which is a shame since that would be the most viable option. That is if you already own one, cause I don't think people are going to buy one just to play this game with it. You never know though.