I have Itead Dual Stepper Driver. There is possibility to connect it with i2c interface but I don't know how to program it.
How did you get the impression that this shield is controllable by I2C? I didn't find any mention of this functionality and I cannot see any chip on it that would support your view.
You control that shield by simply setting digital IOs, a simple example sketch is available in the download section of the linked page.