In /sys/class/misc/customvoltage the ARM and internal voltages for the different frequency states are set by passing a string of voltage values in mV to armvolt or intvolt (for example 'echo "1250 1200 1000 950 950" > armvolt').
This should work no matter the number of frequency states implemented in the kernel. This replaces the custom UV interface most kernels have implemented
Changes to the source: http://www.pastie.org/2806507
Made Custom Voltage compatible with the typical CPUfreq UV interface (UV_mV_table) found in many kernels thus making it compatible with SetCPU and similar tools.
Added the entries 'max_arm_volt' and 'max_int_volt' to the sysfs interface which can be used to change the maximum values allowed for the ARM and internal voltages.
No further patches will be published here. I have set up a git repo for all my tweaks. Each mod has its own branch to keep the tweaks cleanly separated and one can simply pull the latest patches from the corresponding branch.