To change the keyboard layout from std US/UK layout, open the terminal (ctrl-alt-t) and type

setxkbmap se

(se gives you the Swedish keyboard layout - use a different country code for other local keyboard layouts. Whatch inside /usr/share/X11/xkb/symbols) This setting is only active until you reboot. To make it permanent, include it in some startup script (that I think has to be run after X is started). One place is in /etc/X11/chromeos-xsession and then it must be before the exec rows. I put it just after xscreensaver and that works great, but it makes your language changed only after the login screen.

To change the keyboard layout before the login screen, you have to update /etc/X11/xorg.conf (open a terminal (ctrl+alt+T) and command sudo nano /etc/X11/xorg.conf with password: facepunch) and add a line inside the block of keyboard stuff:

Option   "XkbLayout"   "se"

UPDATE: It appears you should add languages in Chromium options pages in order to get more keyboard choices: http://groups.google.com/a/chromium.org/group/chromium-os-discuss/browse_thread/thread/5bcfac0ab1c02af4