I am a B-737 Capt for Southwest, and I am also a fan of the current generation of flight sims (My kids are aces on CFS-2 already!).
It is my opinion, that given the circumstances on tuesday, that a few hours of manual study, coupled with a few hours of PC sim time and actual light plane flying, that it is entirely possible to do what they did.
They took the aircraft in trimmed cruise/climb flight, in near CAVU conditions. Anyone with rudimentary flying skills would be able to either disengage the autopilot and steer it towards a huge 1200' target. A Boeing is not a fighter. If they had any clue, they could just have engaged heading mode and used the AP. As it was CAVU, they didn't need to know much beyond how to disengage the AP and operate the yoke. Any Cessna pilot could do that. I also belive that if you can fly one of the better PC flight sims, then you can also do that.
They weren't worried about altitude, heading, or flight plan deviations. They also weren't required to shoot Cat2 ILS approaches, V-1 cuts, holds etc......
My best friend is a tracon controller in JFK, and was working departures during the incident. He said it was pandemonium (obviously!) for a few minutes. They had turned off the x-ponder on one of them, and the other stayed on it's original sqwawk.
Truly scary times we are living in folks!