The Cessna 340 is a class of aeroplane (MEP), not a type . However it is pressurised.
If you had a valid MEP rating, and had difference training for the aircraft systems, and it was being operated on an AOC, and you were qualified under the AOC to fly it, and the autopilot was U/S making a second pilot a legal requirement for AOC work, then and only then,you could probably log the time.
However, as you can see there are a lot of 'ands' .If it is an AOC operation, speak to the flight ops inspector for his opinion.