Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Type
PFO_TYPEParameter: Constant Speed
PFO_CONSTSPEEDParameter: Spring Speed
PFO_SPRINGSPEEDParameter: Follow Position
PFO_POSITIONParameter: On
IN_PFO_ONParameter: Animation Time
IN_PFO_ATIME