Hi Thunderblade.
You are on the right track, but one small correction to your original post. Enhanced Intel SpeedStep® Technology doesn’t change the multiplier, it changes the P-State of the processor. A P-State is specified combination of voltage and frequency.
P-states cannot be modified (meaning you can’t change the voltage/frequency combination for say P-1), but you can modify how aggressively the OS manages the transitions. Microsoft® has a very good article here: http://download.microsoft.com/download/3/0/2/3027D574-C433-412A-A8B6-5E0A75D5B237/ProcPowerMgmtWin7.docx.
You will find a list of Processor Power Management settings starting on page 27. You will need to use Powercfg.exe to un-hide some of them using the same general syntax you noted in your second post.