I'm interested in this, but don't have a greek/russian/... keyboard to test. I have gone:
sudo apt-get install console-data
and accepted the default 'Don't touch keymap' in the dialogue that comes up. Then I can switch between different western European layouts with:
sudo loadkeys uk|fr|de
but if I try:
sudo loadkeys gr
I don't get Greek letters, just Latin qwerty. If anyone could test with a non-Latin keyboard, that would be a step forward, and we could then look at switching settings in the GUI. The keyboard has to be directly connected, of course, these settings will not change what you see in a SSH terminal.