How to communicate to i2c driver in Qnx

we have a mgt5200 controller on which is connected an i2c interfaced RTC clock. Our I2c driver is working fine. The problem is we are not able to set the registers in the RTC. I want to set the individual registers in the RTC. Can any one tell how to do that. Any info will be helpful.

Thanks and Regards
Shailendra Carpenter
Wipro Technologies