Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Filepath
ID_VOLUMESET_PATHParameter: Save
ID_VOLUMESET_SAVEParameter: Reload
ID_VOLUMESET_RELOADParameter: Detach
ID_VOLUMESET_DETACH