Sorry I did not study thoroughly your solution, I thought I could put opengl32.dll implementing software parallel rendering on CPU into a x64 folder nearby dxglxfg.exe and get shaders working but dxglcfg does not seem to work that way. Do I misunderstand what dxgl actually does?
The version of opengl32.dll I am using is actually a mesa3D based and supports at least OpenGL 3.3 which I tested with my GLSL v1.5 shader based apps. My intention is to run DX based apps with the shaders on virtualbox using software rendering via mesa 3D.