Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Global Matrix
GV_MG_SAMPLEEFFECTOR_IMATRIX
Parameter: Color
GV_MG_SAMPLEEFFECTOR_ICOLOR
Parameter: UV
GV_MG_SAMPLEEFFECTOR_IUV
Parameter: Weight
GV_MG_SAMPLEEFFECTOR_IWEIGHT
Parameter: Time
GV_MG_SAMPLEEFFECTOR_ITIME
Parameter: Global Matrix
GV_MG_SAMPLEEFFECTOR_OMATRIX
Parameter: Color
GV_MG_SAMPLEEFFECTOR_OCOLOR
Parameter: UV
GV_MG_SAMPLEEFFECTOR_OUV
Parameter: Visibility
GV_MG_SAMPLEEFFECTOR_OVISIBLE
Parameter: Weight
GV_MG_SAMPLEEFFECTOR_OWEIGHT
Parameter: Time
GV_MG_SAMPLEEFFECTOR_OTIME
Parameter: Strength
GV_MG_SAMPLEEFFECTOR_OSTRENGTH