Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Type
ROLL_TYPE
Parameter: Laziness
ROLL_LAZINESS
Parameter: Axis
ROLL_AXIS
Parameter: Source
ROLL_SOURCE
Parameter: Invert
ROLL_INVERT
Parameter: Stretch
ROLL_STRETCH
Parameter: On
IN_ROLL_ON
Parameter: Animation Time
IN_ROLL_ATIME