Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: SETOBJECT_OBJ
SETOBJECT_OBJParameter: File
SETOBJECT_FILENAMEParameter: Azimuth
SETOBJECT_AZIMUTHParameter: Altitude
SETOBJECT_ALTTUDE