In case you haven't watched the movie: I go to Brinstar, save in the first available save station, then kill myself. I make a backup of that save and then go on as if nothing happened.
Later on I save in Tourian, right before Mother Brain, then kill myself again. And I reload in Brinstar. I then go down to the room with the fireflies that lead to a missile recharge (you know, that utterly useless path that nobody ever takes because there's nothing worthwhile in it? That one) and kill myself there. Then I load my game in Tourian, glitch to the outside of the room, and magically warp past Mother Brain.
Going to the title screen throws a ton of data where room data is stored during gameplay. Some of that data can be used as doors to other rooms. The only problem with this is that doors generated from random data usually have a BTS of 00, or a BTS that causes the game to crash. A BTS of 00 means it goes to the room on the right, which doesn't do me any good. I had to find a room that had background data that set a BTS attached to one of those generated doors to 01 instead. Which was why I had to go to that room in Brinstar.
I had to be careful about the path from that room to where I used it in Tourian, though. I couldn't leave out the door because the giant elevator room would overwrite the precious 01 BTS. Clearly, my only option was to kill myself and go straight to he- Tourian.
