Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Transform
MGEXTRUDEDEFORMER_MODE
Parameter: Extrusion Steps
MGEXTRUDEDEFORMER_STEPS
Parameter: Polygon Selection
MGEXTRUDEDEFORMER_SELECTION
Parameter: Sweep Spline
MGEXTRUDEDEFORMER_SPLINE