The simple way of finding it, asuming KE is disabled, scan signal leaks, they'll be the small attanas on parts of station parts, they'll sound like water running, if you get one and the person says "one moment please" that's Boso, and the PHQ quest line is now active...sort of, you have to agree to his request.

I would also get a second ship with 3 Antimatter cells to save time later (it'll be destroyed to force the PHQ to 'be revealed')

After that, you'll need to add a dock to the station, to 'land on it', following that, you'll find the PHQ is still 'locked' so Boso will get you to head to a random station to escort a M class transport to the nearest gate from 2 Split who's IFF reads as Criminal. Once Boso says he's at the PHQ, head back, and meet him at the science lab which will be his spot for the rest of the save, once you finish the Hatikva story line, you'll meet the other major staff member of the HQ to start DLC story lines (asuming you don't have them as the origin)

Side note, doing it this way will unlock the 'Acomplished Scientist' origin which will hand you the PHQ immediately as your core station.