follow the gas door release cable...sort of
Sorry no pictures, I kind of made this one up as I went along, but basically you can follow the cable release for the gas filler door most of the way.
To get the antenna inside, make a very tiny slit in the rubber boot that the hatch wiring goes through. Gently stretch the hole open to slide the antenna jack through, and pull the rest of the wire. With just the tiny slit, the boot will close up nice and waterproof around the wire. Then remove the rubber trim that seals the inside liner to the body panel and run the antenna around to the left side where the jack is...and the gas filler door cable.
Once inside, open up the little hatch that hides the jack. Go to the left rear door, pull back the rubber gasket that seals the interior panels to the sheet metal, and slide a fishtape back to the jack area and pull the wire to that point. Once you get to the rear doorway, keep running it down to the door sill behind the inside panel. Then remove the two hard plastic threshold pieces in both the front and rear doors. You will see there channel with retainers where other rear wiring goes along with the gas door cable. Run the cable there and just up to the front seat.
At that point I noticed the stock antenna really could use another 5 feet in length, but this seemed to be the shortest accessible route. So I removed the two sections of the center console (they both just pull out with a gentle yank). There is one screw on the side that will loosen up the frame for the console so you can run the fishtape under the carpet to the threshold. Pull the antenna through to that point, and you should have enough to mount just about anywhere around the center console area.
Two things -- be gentle with the antenna and the jack if you use the fishtape. You definitely don't want to have to go buy a new one at this point. And also there are instructions posted somewhere on the net that will show you how to get to the radio to do a direct wiring or one of those modulators.
I bought a Peripheral brand interface for direct wiring at about $110. Theirs comes with several harnesses so you know you will have the right one for your vehicle. Set the dip switches for your application and plug the Y-harness in between the radio and amp. There is plenty of room in the radio cavity to fasten the brain with double side tape, and reinstall the radio. The Peripheral allows for either an 1/8 stereo jack or 2 RCA jacks for input. I ran the 1/8 line beside the AC controls down to the console, and then you can do what you want from there.
By the way, Arkon makes a great flexible goosneck mount that just attaches to the seat bolt mount on the floor, if you are someone that doesn't want to drill or mess up the dash.
Good luck, sorry for the long post.