AmdMsrTweaker is a command line tool for Windows which allows to reprogram the P-States used by various CPUs and APUs of AMD for their Cool&Quiet power saving technology.
If you just want to use the tool, just download the precompiled binary and follow the directions in the readme.txt file:
The project is set up using Visual Studio 2010. Using the Express Edition is also possible, though for compiling 64bit builds the respective Windows SDK is needed.
Additionally you need to download the WinRing0 library, which is not included in the Git repository:
Just check out the repository, extract the WinRing0_lib.zip file and then you should be able to compile it in Visual Studio.