Unfortunately it's not that easy.
When you include the OpenGL Header, the engine will not automatically use OpenGL (correct me if I'm wrong). It's just there if you want to write your own renderer in lite-C, which you probably don't want to. Calls to wglSwapIntervalEXT(1) will end with an error or even a crash when there is no OpenGL Context defined. The function should not be able to change VSync for a DirectX renderer as Acknex.

Future engine version will need to use OpenGL, when they want to support publishing to android. I don't expect that will ever happen, at least not this decade .