Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Start Angle
ROTATESURFACE_ANGLE_STARTParameter: End Angle
ROTATESURFACE_ANGLE_ENDParameter: Rotation Axis
ROTATESURFACE_LINK_AXISParameter: Reverse Rotation
ROTATESURFACE_INVERT_AXIS