Well as topic says, is there any mods for ps3?
And if there is, how do i get them? and install them?

No, there is not.

Mods are for the PC version only. Shortly before Skyrim released Todd did say they would like to bringing modding to the consoles, but there were still far too many issues to work through first. Not the least, both Sony and Microsoft currently say no to modding of this kind of scale.

edit: It may be at least the next generation of consoles before we even see modding beyond what can be done with the far more restrictive editors of Farcry 2 and Little Big Planet. Maybe longer

ok, thanks for answer

The issues are entirely bureaucratic (well, and $$$-driven), not technical. Microsoft and Sony say no intentional in-built modification support; want to release a game on their platform, play by their rules, and so all the game companies do.

Queue

I would blame it on the Trophies/Achievement system. You can see that there are many mods available on PC that make getting achievements a lot easier. Not to mention that MS and Sony would probably want to be paid in some fashion.

Nope. And I doubt Sony or Microsoft will ever allow them but if they do, it will be with the release of the nextgeneration consoles in...whenever they come out. I think the unofficial estimate is 2014.

I doubt that. The Witcher 2 has an arena side-game with an online leaderboard, and if you use mods that alter gameplay in any way you're blocked out of the leaderboard.
Even New Vegas has a system wherein you're barred from getting achievements if you use a console command cheat, I'm pretty sure.
As for wanting to get paid, mods vastly increase the life of a game, and by extension sales.

Thats really a pointless effort since you can use a mod cheat instead. Lets say you write a script that gives you all the achievments when you start the game.

Question answered, I am closing this before it deviates into discussion of console modding.