It's definitely doable. the only question is how. I've done similar work on a mercedes and a bmw. The process is pretty much the same: determine the location for your new unit, open up the necessary panels along the way to lay in your wires, find wires that'll supply power to your unit, hook up everything and put back the panels. It's more of a challenge if you've never done it, but the more you try, the easier it gets.
Of course, you can always get your local radio shop to do it for ya, shouldn't cost more than 50~100 bucks for the installation.