We do not have any example code for using our TB6612FNG Dual Motor Driver Carrier to control a stepper motor. You might be able to use the code from this forum post as a basis to write your own code for doing so. Please note, you should use Jeremy's revised code as a basis for your code since it adds some improvements.
A simpler route would probably be to use a dedicated stepper motor driver, which offers additional benefits such as current limiting and is much easier to control. We have some example code for the Arduino that is compatible with our drivers in our "Setting the Current Limit on Pololu Stepper Motor Driver Carriers" blog post as well.