How do I mod Fallout 3 for the PS3?

I have Fallout 3 for the ps3. I already beat the game a million times, and would like to know how I could mod it. I will not jailbreak it, out of the question. I was wondering is there was a way I could do it with a type of USB or similar device. If you could please tell me where I can download the mod, and how to install it on the PS3. Thanks.