Just my opinion, but going the GS route (civilian for the govt) is very, very competitive. They hire very few every year and many are hired on for :
1. Military experience
2. Security clearance.
The most popular site is usajobs.gov. It will allow him to look not only by the job, but also the state. Beware though that many of the jobs are being filled by those that are already there, and by law they must advertise the position. I.E. A GS 12 position may be open in an office, as well as the GS 10. Many times the GS 12 position is being filled right now by the GS10 (acting as the GS 12). Thus, chances are the GS 12 position is filled and the real opening is the GS 10. Don't over reach.
I am not sure I agree with Day Tripper regarding AF recruiters for OCS. Our friends DS just walked into the local AF recruiting office and stated to an enlisted recruiter he wanted to go to OCS for a rated (flying) position. They set him right there. For ROTC this is true because they do not deal with scholarships typically, but for OCS they do deal with that.
~ Caveat: Our friend was living in what I do not consider a large metropolitan area.
Has he thought of applying FT Guard? For the AF you apply to the unit...think like applying to any corporation.
Is he willing to relocate? If so, look into companies like Lockheed, Raytheon, Rand, L3 Comm. All great defense contracting companies that like engineering majors.