diff -uNr xserver-common-1.33.orig//X11/xserver-common xserver-common-1.33/X11/xserver-common
--- xserver-common-1.33.orig//X11/xserver-common        2010-04-28 23:27:10.000000000 +0200
+++ xserver-common-1.33/X11/xserver-common      2010-04-28 23:29:07.000000000 +0200
@@ -192,3 +196,8 @@
 if [ "$XSERVER" != "Xorg" ] ; then
     ARGS="$ARGS $MOUSE"
 fi
+
+# let a local script modify the variables                    
+if [ -e /etc/X11/xserver-system ] ; then                    
+       . /etc/X11/xserver-system                    
+fi