Forcing NVIDIA GPU programmatically in Optimus laptops

Question

I'm programming a DirectX game, and when I run it on an Optimus laptop the Intel GPU is used, resulting in horrible performance. If I force the NVIDIA GPU using the context menu or by renaming my executable to bf3.exe or some other famous game executable name, performance is as expected.
Obviously neither is an acceptable solution for when I have to redistribute my game, so is there a way to programmatically force the laptop to use the NVIDIA GPU?

I've already tried using DirectX to enumerate adapters (IDirect3D9::GetAdapterCount, IDirect3D9::GetAdapterIdentifier) and it doesn't work: only 1 GPU is being reported (the one in use).

Answer 1

According to http://developer.download.nvidia.com/devzone/devcenter/gamegraphics/files/OptimusRenderingPolicies.pdf starting from 302 drivers it is enough to link statically with one of the following libraries: vcamp110.dll, vcamp110d.dll, nvapi.dll, nvapi64.dll, opencl.dll, nvcuda.dll, cudart*.*, or to export a NvOptimusEnablement variable in your program:

extern "C" {
    _declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
}