The xorg.conf file is in /etc/X11/. So you can view the file by typing on the command line: sudo view /etc/X11/xorg.conf. I guess you will need a usb keyboard to do this. If you dont have one then i would try first, the method at http://ubuntuforums.org/showthread.php?p=4152003
Basicly when you boot the system you will have a screen that looks like this one.
Press any key within three seconds.
The you will get a screen like this one.
Use your arrow keys to select the kernel line. Press e.
You can then edit the boot options. at the end of the line add locale=fr_FR i8042.reset
press enter. then press b. it will boot with the new options.