question for cpu voltage scaling in linux

Hi,

Sorry for posting cpufreq, linux-acpi as well.

I want to change voltage and frequency seperately.
With cpu-freq, i can change frequency, but cannot change voltage AFAIK.

Can I do this using cpu-freq?

If possible, how can I set voltage with the fixed value? If not, is there any way to do that?

FYI, i'm using intel i7-core(nehalem) and ubuntu 10.10. FYI2, i found out i can do using IA32_PERF_CTL register, but there's no detail from intel.
FYI3, can i change P-state table so that i can only change voltage in P states?

Thanks,
mihn