coefficients of distortion function...

From this thread it looks like they might be:

param_named HmdWarpParam float4 1.0f, 0.22f, 0.24f 0

I got those numbers by creating an OVR::Util::Render::StereoConfig object and calling it's GetDistortionK() method. The numbers seem to be the default for no hmd detected.
(If you have a hmd connected, you can get it's HMDInfo and give it to the StereoConfig to set it up)

I did this:

if(m_oculus)
	{
		m_oculus->GetDeviceInfo(&m_oculusInfo);
		m_stereoConfig.SetHMDInfo(m_oculusInfo);
	}

	float d1 = m_stereoConfig.GetDistortionK(0);
	float d2 = m_stereoConfig.GetDistortionK(1);
	float d3 = m_stereoConfig.GetDistortionK(2);
	float d4 = m_stereoConfig.GetDistortionK(3);

Perhaps of little practical benefit to determine the magic coefficients ;) , but an insight nonetheless, the distortion function is the first four terms of a Taylor series expansion of the sin() function (multiply in the "r"):

sin(r) ~= k_0 r + k_1 r^3 + k_2 r^5 + k_3 r^7 + ...

I believe the Rift uses spherical plano convex lenses, and this produces a radially symmetric distortion, thus the shape of a circle becomes relevant, which sin() captures :)

@zalo - thanks, that is exactly what I was looking for! I am python coder with very different needs from typical OVR users, would have to install MSVC, which You saved me from :)