Trying to help a friend of Jim Hennessey's. A gentleman named Gary is the nephew of a WWII vet who is looking for info on uncle's unit, the 544th Ordnance Co.
Here's what Gary had to say:
The town where they captured the Germans in US ARMY uniforms was Sprimont,
Belgium. This from Capt Jules Lipcon (he is still alive and living in New Jersey). I was in Sprimont in Dec 04 with the VBOB tour.
I advised him where to go for further info, but if anyone has any tidbits in the interim, it would be highly appreciated. 
Wrote to my friend Henri and this is what he had to say:
Dear Marion,
I am sorry but I don't possess information concerning the 544th Ordnance Co
but I am sure that this unit was at Sprimont before and during the Battle of
the Bulge.
As attachment, a picture showing three German soldiers captured on 17
December 1944 at Aywaille (neighbor's village of Sprimont).
These Germans soldiers were sentenced to died and executated on December 23,
1944 at Henri-Chapelle.
Their names are (left to right) Schmidt,Billing and Pernass.
Sincerely
--------------------------------
Henri ROGISTER
22 Rue du Progres
B-4032 LIEGE
BELGIUM
Website: http://www.criba.be
Email: henri.rogister@skynet.be
Notice they are wearing American uniforms.
These spies were part of Skorzenski's special troops who disguised themselves as GI's and inflitrated the American lines.
Steve