ROM Hack Change button mapping NES VC Titles

[The_Hulkster]

Hi,
I'm not going to beat around the bush, hope you don't mind.

Recently got a 3DS and installed the NES VC title Super Mario Bros. 1, 2 and 3.
Unfortunately the button mapping is crap and set to A/X instead of B/Y, which would make so much more sense.

Noticed a bunch more people online have been frustrated with this since about 2013 of something.

Would it be possible to unpack/extract the ROM/emulator, find the button mapping and change it?
As far as I could tell from online sources, every VC title has it's own emulator built in with the ROM.

Any help with this would be appreciated.

 

[AkitoUF]

I'm pretty sure if something could have been done about it, it WOULD have been done about it already.

 

[The_Hulkster]

Apparently the controls can be altered when using the Ultimate NES VC Injector made by @Asdolo .
So why would't it be possible to change it for the original title?

Unfortunately the Ultimate NES VC Injector doesn't map them to the ones I would like to use.