Sorry it took so long to get back ... but it's done.
I finally found the time to rip my dash apart and check it out. There was no 13 pin connection in the back of the stock stereo. So I wired my 2003 Forester with a JVC powered modulator. Crutchfield support assisted me in tapping into the stock stereo's wiring. (Yellow with green stripe is hot, black with red stripe is ground).
Sounds great, even north of Dallas toward Denton, and I'm using 88.3. The static (that faded in and out on the Griffin iTrip) is GONE. Bonus, I can use the volume control on the iPod. Couldn't do that with the iTrip.
To keep it clean, I purchased a 3.5mm female-to-female jack adapter ($5 at Radio Shack) and JB welded it into one of the blank switch plates next to the emergency brake. The modulator's cable plugs in the bottom and snakes under the center console to the glove box where the FM modulator is accessable but out of the way.
Now I just use a Zip Linq 3.5 mm male-to-male retractable cable ($15 at Micro Center) to connect to the hole in the console and the iPod. The iPod sits in the cup holder, in a Belkin TuneDoc.
While I had everything torn apart, I spliced a cigarette lighter adapter in under the dash. I'm in the process of JB Welding a female-to-female firewire adapter into the other blank switch plate. (OK, maybe this is a bit excessive).
Tiny rubber grommets surround all holes for a smooth, finished look. When the power outlet is finished, I'll post some pictures if anyone's interested.