Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Animation
VDBIMPORT_ANIMATION
Parameter: From
VDBIMPORT_FRAME_START
Parameter: To
VDBIMPORT_FRAME_END
Parameter: Group Objects
VDBIMPORT_GROUP_OBJECTS
Parameter: Import to Project Location
VDBIMPORT_RELATIVE