Circuitry Question

How can i modify this circuit so i can control the stepper motor with a button. I would like to have 5 buttons. first button is for 90 degrees second button is for 180 degrees third button is for 270 degrees 4th button is for 360 and the fifth would be for random movement.

How will i place the buttons in this circuit?

2 wire circuit for stepper control

or using this circuit:

4wire circuit

Here is the complete page of the circuit:
http://www.azega.com/controlling-a-stepper-motor-with-an-arduino/ ---- part 1
http://www.azega.com/controlling-a-stepper-motor-with-an-arduino-part-2/ ----- part 2

Hope someone can help me in this one.

How about posting this in the General Electronics part of the forum?