I haven't done it yet, but I am slowly get the bits and pieces in order. And soon as work stop sending me interstate every couple of weeks, I might even get time to finish it ..
I've already ditched the factory head unit for an MP3 player, but the next step is to ditch the MP3 for a in-car computer. So the whole centre bezel is going to come out, and replaced with a newly moulded one which gets rid of the little compartment and cigarette lighter at the bottom, shifts the climate controls down about 3/4", which leaves enough space to mount a 7" wide screen.
If you want to keep the head unit, you should be able to do a similar thing, but instead of mounting an LCD panel, you can extend the 1½ DIN to a 2-DIN, and fit a dash-mount LCD in there.