I doubt it L2 is used for aiming, and if you depress it half the way, it goes to manual aiming, once you get used to it, it works really well, but most of the time you can get headshots by just using auto aim and then pulling back on the right analogue stick
But the simple answer is no, and if you really hate the PS3's triggers, then you can buy things to stick on them, so that they bend the other way







