So far I've noticed that the modules were installed on /usr/local/lib instead of /usr/lib; I've corrected that and also added this to the xorg.conf:
Now Xorg actually loads the module:
[ 2061.816] (II) LoadModule: "mtrack"
[ 2061.816] (II) Loading /usr/lib/xorg/modules/input/mtrack_drv.so
[ 2061.816] (II) Module mtrack: vendor="X.Org Foundation"
but it still not working. I've read the whole thread on the ubuntuforums (http://ubuntuforums.org/showthread.php?t=1730361) but nothing from there was really helpful.