Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Spline
MGSPLINEWRAPDEFORMER_SPLINEParameter: Rail
MGSPLINEWRAPDEFORMER_RAIL_SPLINEParameter: Axis
MGSPLINEWRAPDEFORMER_AXISParameter: Strength
MGSPLINEWRAPDEFORMER_STRENGTHParameter: Offset
MGSPLINEWRAPDEFORMER_OFFSETParameter: From
MGSPLINEWRAPDEFORMER_FROMParameter: To
MGSPLINEWRAPDEFORMER_TOParameter: Mode
MGSPLINEWRAPDEFORMER_LENMODEParameter: End Mode
MGSPLINEWRAPDEFORMER_MODEParameter: Scale from Rail
MGSPLINEWRAPDEFORMER_RAIL_SCALEParameter: Size
MGSPLINEWRAPDEFORMER_SIZEParameter: Size Strength
MGSPLINEWRAPDEFORMER_SIZESTRNParameter: Spline Size
MGSPLINEWRAPDEFORMER_SPLINESIZEParameter: Spline Size Strength
MGSPLINEWRAPDEFORMER_SPLINESIZESTRNParameter: Rotation from Rail
MGSPLINEWRAPDEFORMER_RAIL_TARGETParameter: Up Vector
MGSPLINEWRAPDEFORMER_UPVECTORParameter: Banking
MGSPLINEWRAPDEFORMER_BANKParameter: Rotation
MGSPLINEWRAPDEFORMER_ROTATEParameter: Rotation Strength
MGSPLINEWRAPDEFORMER_ROTSTRNParameter: Spline Rotation
MGSPLINEWRAPDEFORMER_SLINEROTATEParameter: Spline Rotation Strength
MGSPLINEWRAPDEFORMER_SPLINEROTSTRNParameter: Fix Bounding Box
MGSPLINEWRAPDEFORMER_FIXBBParameter: Bounding Box Center
MGSPLINEWRAPDEFORMER_BB_CENTERParameter: Bounding Box Size
MGSPLINEWRAPDEFORMER_BB_RADIUS