Well, we're always saying that GC is a place to learn, and I don't know enough about the NPHC. Unfortunately, we don't have any NPHC orgs on my campus at this time.
We had some women who were interested in AKA, but I'm not sure what happened to their efforts.
As a disclaimer, neither I or anyone I know is currently pursuing membership in an NPHC org. Nor do I want to know information that is privileged to members of NPHC orgs!! 
From reading the websites of the four NPHC sororities, I have gathered this much: Those who meet the requirements of the particular sorority they are interested in attend a "rush" event. They also must fill out paperwork on their qualifications. Then, the sorority makes a decision as to membership. Next the pledges/new members (not sure of the appropriate terminology) are revealed to the campus/public as members of a new line. This is a surprise event--no one knows until then who the members of the line will be.
Is this the general process for NPHC intake? Did I leave anything out/make mistakes? I'm really curious to learn more about your orgs and become more well educated. I understand there is a lot I can't know, so if I'm out of bounds, let me know. I was curious about what happens when a line is revealed, what your rush events consist of, etc.