Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Type
ROLL_TYPEParameter: Laziness
ROLL_LAZINESSParameter: Axis
ROLL_AXISParameter: Source
ROLL_SOURCEParameter: Invert
ROLL_INVERTParameter: Stretch
ROLL_STRETCHParameter: On
IN_ROLL_ONParameter: Animation Time
IN_ROLL_ATIME