Keyboard for player2 in Rebirth

Once I read, that second player can play only with gamepad. So, the problem is that I don't have a gamepad, and I don't want to buy it, but I really want to play with my friends together. I want to ask: Can we play together from 1 keyboard? (We know what to do, so for us it will be comfortable in any way ;)). If not, is it possible to add this option before the game get released?