Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Preset
XMBSUBSURFACESHADER_PRESET
Parameter: Color
XMBSUBSURFACESHADER_DIFFUSE
Parameter: Strength
XMBSUBSURFACESHADER_STRENGTH
Parameter: Shader
XMBSUBSURFACESHADER_SHADER
Parameter: Path Length
XMBSUBSURFACESHADER_LENGTH
Parameter: Red
XMBSUBSURFACESHADER_LENGTH_R
Parameter: Green
XMBSUBSURFACESHADER_LENGTH_G
Parameter: Blue
XMBSUBSURFACESHADER_LENGTH_B
Parameter: Mode
XMBSUBSURFACESHADER_MULTIPLE_MODE
Parameter: Enabled
XMBSUBSURFACESHADER_MULTIPLE_ENABLED
Parameter: Fast Evaluation
XMBSUBSURFACESHADER_CACHE_INTERPOLATION
Parameter: Sample Density
XMBSUBSURFACESHADER_CACHE_SAMPLE_DENSITY
Parameter: Smoothing
XMBSUBSURFACESHADER_CACHE_SMOOTHING
Parameter: Threshold
XMBSUBSURFACESHADER_CACHE_ERROR
Parameter: Separate Color Channels
XMBSUBSURFACESHADER_DIRECT_SPLIT
Parameter: Minimum Threshold
XMBSUBSURFACESHADER_DIRECT_RATIO
Parameter: Custom Sampling
XMBSUBSURFACESHADER_MULTIPLE_CUSTOM_ENABLED
Parameter: Sampling Subdivision
XMBSUBSURFACESHADER_MULTIPLE_CUSTOM_SAMPLING
Parameter: Enabled
XMBSUBSURFACESHADER_SINGLE_ENABLED
Parameter: Separate Color Channels
XMBSUBSURFACESHADER_SINGLE_SPLIT
Parameter: Trace Shadow Rays
XMBSUBSURFACESHADER_SINGLE_TRACE
Parameter: Phase Function
XMBSUBSURFACESHADER_SINGLE_PHASE
Parameter: Custom Sampling
XMBSUBSURFACESHADER_SINGLE_CUSTOM_ENABLED
Parameter: Sampling Subdivision
XMBSUBSURFACESHADER_SINGLE_CUSTOM_SAMPLING
Parameter: Fresnel Reflectivity
XMBSUBSURFACESHADER_FRESNEL
Parameter: Dithering
XMBSUBSURFACESHADER_DITHER
Parameter: Index of Refraction
XMBSUBSURFACESHADER_IOR
Parameter: Compute GI Contribution
XMBSUBSURFACESHADER_LIGHTS_GI
Parameter: Use Lights
XMBSUBSURFACESHADER_LIGHTS_MODE
Parameter: Lights
XMBSUBSURFACESHADER_LIGHTS
Parameter: Strength
XMBSUBSURFACESHADER_GPURENDER_SSS_WEIGHT
Parameter: Texture
XMBSUBSURFACESHADER_GPURENDER_SSS_WEIGHT_SHADER
Parameter: Preset
XMBSUBSURFACESHADER_GPURENDER_PRESET
Parameter: Scatter Color
XMBSUBSURFACESHADER_GPURENDER_SURFACE_COLOR
Parameter: Texture
XMBSUBSURFACESHADER_GPURENDER_SURFACE_COLOR_SHADER
Parameter: Scatter Depth
XMBSUBSURFACESHADER_GPURENDER_RADIUS_SCALE
Parameter: Depth Color
XMBSUBSURFACESHADER_GPURENDER_RADIUS_RGB
Parameter: Phase
XMBSUBSURFACESHADER_GPURENDER_PHASE
Parameter: Transparent
XMBSUBSURFACESHADER_GPURENDER_IS_TRANSPARENT
Parameter: Emission
XMBSUBSURFACESHADER_GPURENDER_EMISSION_COLOR
Parameter: Texture
XMBSUBSURFACESHADER_GPURENDER_EMISSION_SHADER
Parameter: Intensity
XMBSUBSURFACESHADER_GPURENDER_EMISSION_BRIGHTNESS
Parameter: Enable Multi-Scattering
XMBSUBSURFACESHADER_GPURENDER_MULTISCATTER_ENABLED