Someone, somewhere must have written a guide on how to fit a 1Din sat nav unit into an A3... ideally, with pics and clear explanations... or is that expecting too much?

I am about to book my car in for this work and thought I ought to check to see how hard it actually is. There are only a few connections to make (Alpine N333RRS), but I reckon the dashboard has to come out to get to everything.

Has anyone done this kind of job before, or got an idea where to find a 'how to' guide - or know what sort of time this really takes?

Just don't want to get ripped off (again) by the local ICE dealers...