The good tutorial that was up there isnt there any more.
But doing the LED mod isnt as hard you you think. Get you LEDs together and one resister. Solder the resister to the +5v on the controller.
Take some wire and solder it to the leads of the LEDs than hot glue them in place where you want them. Make sure they work before you do this though.
After you have all your LEDs in place run the wires to the + and - points on the controller. Put it all back together and test it out.
If I can snag a digital from a friend of mine with in the next two weeks I'll make a better tutorial for this than whats up on X-S all ready. I will have my Crystal Pack XBoxes here on Friday, so I will have some conrollers I can screw around with.