At this point we are not developing adapters for the USB header on our NUcs but you can get one on the market that has the configuration as per USB header Pin layout. Check page 48 here:
http://downloadmirror.intel.com/23089/eng/D54250WYB_D34010WYB_TechProdSpec06.pdf
By any chance have you tested the USB header on another system? This will help us discarding other things.
Kevin M