Lol. The polar bear was a joke. It was just heavy duty "steel reinforced" epoxy putty (apparently it has real steel in it for strength - it IS slightly magnetic, so it probably really does).
Anyway, the job is now done. Took 45 minutes to pull the manifold off, and swap out the last few plugs. Although, in retrospect, I should probably have run a tap through one of the holes, as the thread was a bit sticky on the way out and back in. Oh well, that set of plugs were good for 130k; I'm pretty sure changing these will be someone else's problem.
You wouldn't believe the amount of crap and oil that came out of the manifold. The mating surface needed a really good clean with carb cleaner. I'm guessing this is all the filth aspirated from the PCV.
Interestingly, the plugs from the bank 2 were a LOT sootier than the ones from bank 1 (photo). (Fuel trims are at about -8% on bank 1, and -2% on bank 2; I'm hoping that this doesn't mean the AFRs are on the way out).