Anyone knows of ways to play NTSC games on PAL NES and SNES?

[sennaho]

Ok, so that makes me play the Japanese NES games, but do you know how to play the NTSC NES games? (the american ones)

And how can I mod the NES?
I found a modded nes on a website I´m maybe gonna get, but If I could do it myself to one of my NES consoles it would be easier and cheaper!