Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Type
WOODSHADER_COLOR_PRESET
Parameter: Color
WOODSHADER_COLOR
Parameter: Scale
WOODSHADER_SCALE
Parameter: Stretch
WOODSHADER_STRETCH
Parameter: Ring Scale
WOODSHADER_RING_SCALE
Parameter: Grainy
WOODSHADER_GRAINY
Parameter: Grain Scale
WOODSHADER_GRAIN_SCALE
Parameter: Wavy
WOODSHADER_WAVY
Parameter: Wavy Scale
WOODSHADER_WAVY_SCALE
Parameter: Shift
WOODSHADER_SHIFT
Parameter: Annual Rings
WOODSHADER_RINGMODE
Parameter: Wavy Rings
WOODSHADER_RING_WAVY
Parameter: Wavy Rings Scale
WOODSHADER_RING_WAVY_SCALE
Parameter: Type
WOODSHADER_SIMPLE_TYPE
Parameter: Color
WOODSHADER_SIMPLE_COLOR
Parameter: Frequency
WOODSHADER_SIMPLE_SCALE
Parameter: Turbulence
WOODSHADER_SIMPLE_TURBULENCE
Parameter: Legacy
WOODSHADER_LEGACY