[Matrixdude]

Yes you can use however many hands you want to.

In the settings tab (in the top right hand corner of the game screen) there are four spots under "Key Configuration" in which you can assign each arrow to a different key on the keyboard.

Many people, including myself, set the keys up with A and S for the left hand and K and L for the right hand.

This makes it easier to hit fast patterns and I definitely recommend using two hands.

You may also just use the arrow keys and play "Index" style using just your index fingers on both of your hands. It all comes down to personal preference so tweak around with it and see what suits you best!