The "checkbox" mentioned previously in this thread was a modification applied to Arduino IDE 1.0.5:
Arduino IDE 1.0.x did not have the custom board options feature.
I think it would be more appropriate to do that in a 3rd party platform targeted to more advanced users. If one doesn't exist already, such a platform could be created with only a few files thanks to the referencing feature.
Nice! I also find this stuff very interesting, but expect that not everyone will share that opinion.