OS X has different power management scenarios for different Mac models. These scenarios have different number of C/P states available in each. You should chose your MacModel according to the CPU used. Find the Mac which has the same or at least most similar CPU to the CPU used in your system and try setting the same model.
I'd recommend MacBookPro 5,3/4/5 since the same CPU P8700 was used in mid 2009 13/15" MacBook Pros.
BTW with Chameleon C/P states generation enabled and the right MacModel set, no speedstep kexts are needed, it should work as is.
Thanks buddy. I'm using MacPro4,1 now and power management works like a charm
I'm a Hackintosh user for more than 3 years and finally I got my system fully working as it supposed to be.
I got all the power states from 798 MHz to 2527 MHz. All I did was to remove NullCPUPowerManagement.kext and VoodooPstate.kext and install this specific version of VoodooPowerMini.kext (Version 1.2.49).
I don't know if it works with other CPUs but it get the job done on a Intel C2Duo P8700 laptop.