so i didnt read that article posted, although i bet it is awesome.
some things i learned about box squats:
-sit back as far as you can. if you think you are far enough, you are not.
-your max will be about 90% of your squat max, so train with lower weights
-go wide!!!! i once saw a lecture with louie simmons that stated that wide stance helps wide stance and narrow stance as it works more of the hips. while narrow stance only helps narrow as it doesnt work all the hips as well.
-pause at the bottom, dont relax. just stop long enough to minimize the stretch reflex effect. this will help greatly on the regular squat when you need to explode out of the hole
you can also follow this:
-vary your stance week to week
-vary the bar week to week
-use bands/chains to help with acceleration
-vary the height, dont go too high if you are raw. i do not believe there is much of a need to go above 2" above parallel, but going way below is awesome