Not sure what LJL061 means by a "neutral setting" -- these are traction motors, not gearboxes -- but if the car is dead it won't hurt anything to tow it with a locomotive. And yes, Tadman, the NICTD cars have motor cutouts just like other electric MU cars.
When towing some old electric equipment, it was sometimes necessary to throw the reverser by hand using the lever under the car to ensure the reverser was set in the direction of travel. This was because if it was set the opposite way, the traction motors would develop dynamic braking effort at speed and resist the motion of the train. New stuff is isolated better, though, and doesn't suffer this problem. And it's certainly not an issue with the AC equipment since reversing is controlled electronically by the traction inverter.