I guess that you need some special program to do this. The task is not that simple. If You ask very nicely one of the programming gurus here will give you a helping hand.
This is an excellent question as I am also looking for a way to do this. I have yet to find an easy way to Hatch surfaces in the drafting side of NX. If you don't have a good enclosed area the the two options for hatching surfaces don't work very well in drafting.
If it is not possible in nx, I thought to do a post processing of the PDFs to convert colors into crosshatch.
But I was hoping that someone has a better solution.