Mence I'm already a step ahead of you, this should've been uploaded hours ago but my connection crapped out on me:
Shiny Egg Chaining Guide
Contains the gist of the details, and I thought you were supposed to accept the 43rd egg, not 42nd, but if it's anything like Radar, it doesn't matter, it should be 40. Whatever!
And take 6 or 7 boxes of eggs, are you serious? I doubt it would take that many just to get ONE shiny...
Mateus, you can hatch as many as you want after taking the 43rd egg. Hatch as many as needed until you get your shiny. Just do not turn off your game, do not Fly, do not encounter Wild Pokemon or Trainers. That's generally the basics.
Right now I'm trying this with my Magikarp on Diamond, I finally got all those eggs rejected and now I'm starting to hatch.
I have 2 shinies from the egg chain thing, Vulpix the first time I tried it, and now Munchlax. I'll be honest: Munchlax i think is only the 2nd time I've tried doing it, so, uh, lol?
Now I wonder if I'll get a shiny Magikarp, who knows.