Chrismo,
I respectfully disagree with you. I spoke to a customs official and their view was that importing animals for aquariums was definatley allowed, with some restrictions and exceptions. As someone who lives in montreal and spends a lot of time in New York, I made a point of finding out what I was allowed.
Leheath,
I'm not sure if the rock will start to smell after 5 days, there will definatley be die-off but perhaps not too much. In a car, the water is being moved around while the car bounces around on the road. If you've got a power converter, you might plug in a small powerhead at night to your car's battery (might last till morning, or even if you use a timer and it lasts 4 hours, which doesn't leave them stagnant for too long) then the rocks are in constant circulation.
Will