Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Surface Type
BASESURFACE_TYPEParameter: Make NURBS
BASESURFACE_MAKENURBSParameter: Output
BASESURFACE_OUTPUTParameter: Subdivisions U
BASESURFACE_USUBParameter: Subdivisions V
BASESURFACE_VSUBParameter: Calculate Normals
BASESURFACE_NORMALSParameter: Swap Normals
BASESURFACE_SWAPNORMALSParameter: Enable
BASESURFACE_TESTONParameter: Position U
BASESURFACE_TESTUPOINTParameter: Position V
BASESURFACE_TESTVPOINT