Soak it very well with the pb blaster or liquid wrench, and let it soak overnight (maybe lay the bike on its side to get better penetration).
Get it under tension with the flywheel puller, and try tapping the flywheel with a rubber mallet. You don't want to smack the flywheel with a hammer or too hard, because you can break the magnets loose.
I like the heat idea, too, but be careful - you do't want to melt any wiring or the glue that holds the magnets on. I guess setting it out in the hot sun for a few hours might help a little.
Unfortunately, it is normal for them to feel like they are welded on. Especially on a 20 year old bike.
I had to pull the flywheel on my old '84 back in the day, and I could not beleive how much force it took. When it broke loose, it was loud and sounded horrible - like the flywheel was shattering. But luckily, no broken parts.
You are going to need a lot of torque on the puller - good luck!