I've already completed the game 3 times and I only recently found out about Soft Resetting. I wanted to try it but after 17 on Heatran, I got really Impatient.
If anyone has an easily explained tutorial on how to soft reset and how to automate this, please tell me because I'm itching to get a shiny legendary.
Best Answer
'Soft-Resetting' just means restarting the game without quitting out first.
Notes
In response to your edit:
What you are effectively doing by soft resetting is dice-rolling until you get a certain number, except in this case the dice has 4096 sides.
To automate the process you would need everything from a program that can tell whether a Pokemon is shiny, to somehow automatically pushing the buttons (using robotics or directly soldering your 3DS). Needless to say, automation is not really an option unless you're willing to do some heavy modification to your 3DS. See BlueRaja's answer for options to do so
If you are adamant about saving time, you could change the Pokemon to be shiny after its caught using a Powersave/Action Replay device. Do note that this is directly cheating and generally frowned upon by the wider community (so is soft-resetting according to some purists but it's less frowned upon than Powersave).