No official cheat codes exist for the PS3 version. Console shooters rarely include cheat menus; the PS3's hypervisor prevents code injection (GameShark/Action Replay) without a jailbroken console (CFW), which bans you from PSN.
Jailbreaking (HEN/CFW) for "mod menus" risks permanent PSN console ban. The online population is low; consider the PC version (Steam) with Plutonium or IW4x clients for modded servers, custom maps, and active communities.