Depends on the MY. I believe it's MY 96 -> the 9K comes with a standard ISO connector anyway so you simply plug the radio in and that's it done. Certainly thats what happened when I fitted a Sony Unit to our saab.
What is the factory system in your car?, I've recently replaced mine, have the Harman/Kardon system, I just replaced the head unit but hooked it up to the original H/K amplifier under the seat, I'm unsure if the connections on a Clarion system are the same though. But is isn't very hard, there is only input/output signal, power and remote switching wires at the amplifier.
I rememeber someone telling me that Best Buy in Nashua NH wouldn't fir their stereo for free because it was too hard. I have the Clarion system with the separate Equalizer. I would also like to know which one I should use.