DXR helpers : ShaderBindingTableGenerator

In the examples and samples it’s been shown how to create a root signature wiht rootparameter tables or pointers but I want to add a D3D12_ROOT_PARAMETER_TYPE_32BIT_CONSTANTS and I don’t know how. I know that I can use this function :
nv_helpers_dx12::RootSignatureGenerator rscG;
rscG.AddRootParameter(D3D12_ROOT_PARAMETER_TYPE_32BIT_CONSTANTS, 0, 0, 4);
But I do not know how should I pass the 32-bit constant data to the shader with for instance the AddRayGenerationProgram function. suppose I have an object of this struct:
struct Transforms
DirectX::XMMATRIX model;
DirectX::XMMATRIX modelView;
DirectX::XMMATRIX modelViewProj;
now should I pass the object to the add program by address? should I cast it to something? every thing I do my buffer doesnt work in my shader code.
please help