Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Strength
MGPUSHAPARTEFFECTOR_STRENGTHParameter: Selection
MGPUSHAPARTEFFECTOR_SELECTIONParameter: Mode
MGPUSHAPARTEFFECTOR_MODEParameter: Radius
MGPUSHAPARTEFFECTOR_RADIUSParameter: Iterations
MGPUSHAPARTEFFECTOR_ITERATIONS