Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Weight Tag
FIELDLAYERMOGRAPH_LINKParameter: Mode
FIELDLAYERMOGRAPH_MODEParameter: Radius
FIELDLAYERMOGRAPH_RADIUSParameter: Distance Falloff
FIELDLAYERMOGRAPH_DISTANCEFALLOFFParameter: Constant Update
FIELDLAYERMOGRAPH_CONSTANTUPDATEParameter: MoData Sub-Index
FIELDLAYERMOGRAPH_SUBINDEX