Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Random Seed
HP_VOLUMEPOS_SEEDParameter: Object
HP_VOLUMEPOS_OBJECTParameter: Type
HP_VOLUMEPOS_TYPEParameter: Depth
HP_VOLUMEPOS_DEPTHParameter: Selection
HP_VOLUMEPOS_SELECTIONParameter: Animation Time
HP_VOLUMEPOS_ATIMEParameter: Position
HP_VOLUMEPOS_OUT_POSITIONParameter: Alignment
HP_VOLUMEPOS_OUT_ALIGNMENT