Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Type
CHR_TYPE
Parameter: Time Factor
CHR_TFAC
Parameter: Variation
CHR_TVAR
Parameter: On
IN_CHR_ON
Parameter: Animation Time
IN_CHR_ATIME
Parameter: Time
OUT_CHR_TIME