No "L3" cheat exists for The Sims Bustin' Out on PS2. You may be misremembering or conflating codes from other games.
Press during gameplay: L1, R1, L2, R2, Up, Down, Left, Right, L1, R1, L2, R2
Then enter codes:
motherlode — §50,000kaching / rosebud — §1,000helpme — Max all skills/statsmoveobjects on — Place objects freelyType code, press Enter. No "L3" button combination is documented for this title.