Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Hull Value
METABALLOBJECT_THRESHOLD
Parameter: Subdivision Viewport
METABALLOBJECT_SUBEDITOR
Parameter: Subdivision Renderer
METABALLOBJECT_SUBRAY
Parameter: Exponential Falloff
METABALLOBJECT_EXPONENTIAL
Parameter: Accurate Normals
METABALLOBJECT_ACCURATENORMALS