This is my First Tutorial i hope it helps..
This was tested only my 4.5 O3DS Palantine CFW (JPN) changed to (EUR) and vice versa. (EmuNAND only) not tested yet on 3DSXL or N3DS becanuse i do not have one
Requirements:
Palantine CFW (How to setup Palantine CFW Here)
3DS Region Swap Files...