Taking all of the advice given, here is what happened today:
I decided to get a six-point socket for the 13mm bolt, and a breaker (just in case), and a six point wrench (just in case).
So then, as I was driving back from Sears through Washington, D.C. suburban traffic, I had an idea.
The car runs. So I could heat up the engine to operating temperature.
But what if I CHILLED the bolt? Like, what if I bought a can of compressed air, did what they tell you never to do and decided to blow on the bolt, WITH THE CAN UPSIDE DOWN? Heated engine (it expands), chilled bolt (it contracts) - that should break the threads, combined with some tapping and AeroKroil.
Then I realized - Radio Shack sells a "component chiller" - a sray can of stuff that freezes whatever it hits to below -50 degrees celsius. I don't even have to hold an air can upside down!
So I stopped by a Radio Shack, and indeed, there was the stuff, for under seven bucks. It's called "Component Cooler".
I idled the car up to operating temperature, and shut it down. I then sprayed the bolt with AeroKroil, and tapped it with a hammer and a punch, just as Morris had suggested. I was prepared to do this for the next couple of days, just as recommened. Then I sprayed plenty of the chiller on it, and put more AeroKroil on the area. No luck. I heated up the car again (ran the engine to 82 degrees), then chilled the bolt again, AeroKroiled it, tapped it, removed the fan to give the breaker more leverage in case I needed it, and the tried the 6-point socket with my small ratchet.
The bolt came right out.
This took only about 20 minutes.
Chilling the bolt (in combination with a good penetrant oil and some tapping) might be the next new trick in getting frozen things apart. I am also going to try the cooling solution before pulling the timing chain rail pins.