Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Function
GV_COLORSPACE_FUNCTION_ID
Parameter: Hue from 0.0 to 360.0
GV_COLORSPACE_HUE360
Parameter: RGB from 0 to 255
GV_COLORSPACE_RGB255
Parameter: Input
GV_COLORSPACE_INPUT
Parameter: Output
GV_COLORSPACE_OUTPUT