Hi,
the FirePro SDK works on Windows 8 as well. You will need cmake to generate the solution and project files and you will need to have the AMD APP SDK installed. http://developer.amd.com/tools-and-sdks/opencl-zone/amd-accelerated-parallel-processing-app-sdk/
To use DOPP you do not need to have the FirePro SDK installed. The documentation that was posted to http://devgurus.amd.com/thread/167683 is still up to date. I attached you the latest version of the sample code. Please note that DOPP is not enable by default you will still need to run enableDOPP.exe as administrator.
Chris