ABC offers a complete set-up of transport and logistics services within the textile industry such as transportation of hanging garments and 'flat pack' to distribution to final destination.
http://esatransindo.com/index_files/Page384.htm

A dedicated, stand-alone distribution and warehousing network for the fashion retail business, specialising in the movement of hanging garments and **flat packed boxed goods**.
http://www.tnt.com/express/en_gb/site/home/services/industry...

http://www.linguee.com/german-english/translation/liegeware....

KARINCA is providing services in many fields from warehousing to value added logistics services both for hanging goods as well as **flat packed, boxed and palletized** merchandise.
http://www.karincalogistics.com/eng/1_2_9.asp?link=14

i'm familiar with hanging wardrobe boxes, so maybe "lay down wardrobe box" or "flat wardrobe box" might work well in this context.

Just "flat-packed goods", short and simple, would be adequate in your context.

"Hanging garments" would be my tip for "Hänge-Versand".


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Note added at 1 hr (2010-08-22 18:32:21 GMT)
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In Schwaig ITG benefits from the largest hanging garment facility of a logistics service provider in Southern Germany. It has a capacity of more than half a million parts for both static and dynamic storage. Additional benefit: hanging garments and flat packed goods are stored at the same location. This leads to consolidated shipments and reduces costs.
http://www.itg.de/ftpdown/itg-motion_06.pdf

hope this is helpful