I know Corsair sells front I/O panels for different cases. Like www.corsair.com/en-in/350d-front-panel-i-o
I have not seen a NZXT one for sell. You can try generic ones to see if they work.
Example:http://www.amazon.com/StarTech-com-3-5in-Black-Multi-Panel/dp/B00AC81FO0/ref=sr_1_2?ie=UTF8&qid=1406613603&sr=8-2&keywords=front+i%2Fo
Otherwise I would suggest buy a USB hub and connect to any of the back ports. You can keep that hub in on your cabinet and use as front USB ports