If you just want to shorten the shifter (without changing the throw), this is very easy. I did this on my car. At least with w5x gearboxes in xa6xs, there is an ugly stick with a fat nice chrome stick stuck on top that the shift knob screws on to. The two are separated by donut-like bushings (to remove vibration/road noise)... but the top bushing is solid. If you loosen the two sticks by patient use of a heatgun & vice, you can then drill through the top bushing and sit them back together to make the shifter slightly shorter. I went a little further and cut down the ugly stick maybe 10mm too. The chrome stick now sits down far enough that it rests on the bend in the ugly stick (hopes this makes sense).
Still looks stock, feels (and looks) a lot better. Some go further by simply not bothering to put the chrome stick back on, and attaching a universal-type shift knob (type with 3 grub screws) directly to the ugly stick. I tried this, but I really didn't like the heap of road noise/lots of vibration/gearbox whine/overly direct feel. The bushings are obviuously there for a reason.