power management - adjust VDD1 by I2C

I am going to control the output voltage based on the software. I
guess i need to do these steps:

1- setting the ENABLE_VMODE bit (VDD1_VMODE_CFG[0]) to zero.

2- write on the STEP_REG field of the VDD1_STEP[4:0] register. This
value determined the output voltage as: Vout = 0.6 + (the value of
VDD1_STEP[4:0] ) * 0.125

These steps are for changing VDD1 since i need to only change the
omap3 core supply voltage. Can you please some one check if those
mentioned steps are correct or not? and Then, the main problem, please
guide me how to access (read or write those registers) for example i
dont know how to enable VMODE to be zero. I am using angstroom linux
kernel for my beagleboard (it includes I2C drivesr as well i2c1 , i2c2
and i2c3 and i guess i2c1 is for vdd1) and i am writing all programs
in C, compile it and execute by the linux kernel.
I need to know how to change those registers?

Thanks a lot