Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Start Angle
ROTATESURFACE_ANGLE_START
Parameter: End Angle
ROTATESURFACE_ANGLE_END
Parameter: Rotation Axis
ROTATESURFACE_LINK_AXIS
Parameter: Reverse Rotation
ROTATESURFACE_INVERT_AXIS