Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Random Seed
HP_VOLUMEPOS_SEED
Parameter: Object
HP_VOLUMEPOS_OBJECT
Parameter: Type
HP_VOLUMEPOS_TYPE
Parameter: Depth
HP_VOLUMEPOS_DEPTH
Parameter: Selection
HP_VOLUMEPOS_SELECTION
Parameter: Animation Time
HP_VOLUMEPOS_ATIME
Parameter: Position
HP_VOLUMEPOS_OUT_POSITION
Parameter: Alignment
HP_VOLUMEPOS_OUT_ALIGNMENT