Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Type
PFO_TYPE
Parameter: Constant Speed
PFO_CONSTSPEED
Parameter: Spring Speed
PFO_SPRINGSPEED
Parameter: Follow Position
PFO_POSITION
Parameter: On
IN_PFO_ON
Parameter: Animation Time
IN_PFO_ATIME