I could see two threads: The Pipe Character and Virtual keyboard layout change/mod? but they don't contain much information. The file to be modified is "/usr/share/X11/xkb/symbols/nokia_vndr/rx-44" (however, see my previous message about the 4th column). And this file will be re-read by the system after killing the /usr/bin/hildon-input-method process that has (most often) the largest PID, as said here.