there's alot of theories on how to do it
but the hex editor thing sounds a little hard
the one i've heard and read is that he used an emulator to play it
in emulators there is a way to play the game at 1/2 1/4 1/8 1/16 the speed of the normal game
still at this rate you'd have to play this game not for 11 minutes but probably an hour just running through it
not to mention that fact that if you die you have to start over again
this explains the jumping on bombs to get one-ups
and explains the fact that he goes back to kill guys that aren't going to even harm him, he just kills them anyways
(in the 8th world the flying stage, kills the guys who pop-up and throw things)
still i wouldn't waste my time, i'd rather play xbox...er real games not emulators hahaha