I have also done things according to that wikipage and it worked after reboot... Maybe didn't you forget to add the first line?
<?xml version="1.0" encoding="UTF-8"?>
And did you have that file there already or did you have to create it?
...but actually even if I activated SHMconfig, touchpad does not work. Of course I have enabled it in Mouse and Touchpad settings... So please let us know if it worked, and if not, how did you solve it