If you want to change keyboard layout for Xorg in piCore, create xorg.conf file in /usr/local/share/X11 (or edit if already exists) and add a section like this:
Section "InputDevice"
Identifier "Keyboard0"
Driver "kbd"
Option "XkbLayout" "hu"
Option "XkbModel" "pc105"
EndSection
It is setting a Hungarian layout for a pc105 keyboard. Replace it with your own settings and add xorg.conf to backup to make it persistent.
You can put a small config file, for example mykbd.conf with the same content to /usr/local/share/X11/xorg.conf.d alternatively.
It is fixing the layout issue, but special keys and key combinations still doesn't work. It is the next step.