Well I gave it a try. Last week I visited the a Malt facility in Bavaria and picked up my 55lb (25kg) sack of Dinkel Malt. I received a great tour of the facility and had a wonderful experience.
I had done my homework by calling the USDA and got directed to the Seeds Not Intended for Planting Manual used by the inspectors. I made sure to have a full copy of the printed manual with me with the page earmarked.
Spelt is a derivative of Wheat so it fell under that classification and for Germany it was listed as an inspect and release category. I also carried a description of Spelt which showed that it was a wheat derivative.
At around 60 lbs my suitcase was overweight but with a business class ticket and a strong frequent flyer record with the airline - no charge (this was key).
I made sure to check the box on the customs form indicating that I was carrying seed, food, etc... which raised some question. The passport control officer asked and when he was told it was malt for brewing he commented that he makes wine and his dad was a home-brewer.
At the USDA inspection area there were definitely some eyebrows and skeptical looks by the officers. However, when I showed the inspection agent the manual and other documentation, he took a look at the grain and indicated that it was fine to proceed.
I get the impression that 99.99% of the shift for these agents are people trying to sneak some sausage or rogue fruit into the country unnoticed which I think puts them in a defensive mood as most people probably try to argue with them.
So now I can say to all that this can be done. I would not recommend doing this unless there is a really unique malt and can not be found in the homebrew supply houses. Definitely do your homework as the regulations vary by malt type and country of origin.
I now have mine vacuum sealed and stored. Need to get a brew day scheduled in the next few weeks.