First of all, this is a tutorial for the 3DS Version.
1. Get your sprite. It's located in "romfs/Model. It's a .szs file.
2. Open the file in Ohana3ds rebirth and export the .bch.
3 Create a new folder (I did it on my desktop).
4. Start ohana3ds (not rebirth) and open the .bch file.
5. export all the textures into the new folder you created.
6 Edit them. Every image is a frame of the animation.
7. If you are finished, import the new images into the opened .bch in ohana3ds and save.
8. Download 3DS SZS Packer 1.1.
9. Start it.
10. The filename has to be the same as that one you replace.
11."SZS save loc" is the output location. I selected my desktop.
12."SZS source folder" is the folder, that contains the edited .bch.
13.Press "Pack SZS" and it should be compressed as .szs.
14 Copy it into "romfs/Model" and overwrite the original. It should work.