Hi!
I have Itead Dual Stepper Driver. There is possibility to connect it with i2c interface but I don't know how to program it.
I mean what data I should sent to - for example - make one step with one of motors?
Only documentation and example code use standard pinouts.
Thanks!
Please provide links to the used hardware.
Ooops sorry 
It's exactly like this one:
http://imall.iteadstudio.com/im120417015.html
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.