Dang, I didn't come across the JazzyAux mod in my initial search... I guess I should have been a bit more thorough. That method is definitely the way to go. I'm happy with my setup though and I had a bit of fun with my project.
I'm a bit late to the party but I just bought a 2005 Outback XT. I was surprised by how challenging it would be to put a bluetooth system in the car so I achieved it in a sort of round about method. I installed a bluetooth amp and a set of relays to switch the speakers over from radio to bluetooth. I recorded my process in case anyone else wants to give it a go.