Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Strength
MGDELAYEFFECTOR_STRENGTH
Parameter: Selection
MGDELAYEFFECTOR_SELECTION
Parameter: Mode
MGDELAYEFFECTOR_MODE
Parameter: Position
MGDELAYEFFECTOR_POSITION_ACTIVE
Parameter: Rotation
MGDELAYEFFECTOR_ROTATION_ACTIVE
Parameter: Scale
MGDELAYEFFECTOR_SCALE_ACTIVE