Getting accented characters working properly

To get all the keys and €s and öōé etc. like in http://wiki.linuxquestions.org/wiki/Accented_Characters

setxkbmap -layout gb -option lv3:ralt_switch

is equivalent to the following in xorg.conf

Option “XkbLayout” “gb”
Option “XkbOptions” “lv3:ralt_switch”

You can select variants from
/usr/share/X11/xkb/symbols/gb