I have tried the offscreen rendering builds - the more recent builds only worked in 32 bit mode and without GPU support. Shouldn't this be possible?
https://msdn.microsoft.com/en-gb/library/windows/desktop/ee913554(v=vs.85).aspx
although it won't share between OpenGL and DirectX, it should allow for a DirectX9 device object to share memory with a DirectX11 device object - from a different thread. (I appreciate the software engineering might not allow this)