Arduino Controlling a stepper motor
I've got to ask here.  Why use a stepper?
This would be fairly easy with two button switches and a regular DC motor.  One switch provides power to drive the motor CW the 2nd motor drives it CCW.  

You would still need to choose a motor with the right torque but IMHO this method would be WAY easier than using a stepper, and arduino, writing code, etc.