i know probaly this is a bad idea, because the roms are different form nintendo DS files but if there a way to hacking the 3ds rom itself to reverse engiried for work on recent emulators maybe would work. i don't want too see commented like "oh man your so stupid is completly impossible" so there a lot possibility maybe work maybe doesn't work. Comments are welcomed of course.
It is impossible for the present to hack 3DS rom for fan editing purpose, in future maybe, but not now. No matter, you can't simply "reverse engine" something new to work on something older. It's like hoping to run a software meant for Windows 7 on a Windows 95 computer. You're overly imaginative.