They are good perks for RP purposes and the LB perk adds the unique spiked knuckles so its good for Unarmed builds....
And w/ BS, you have more then enough Perk-slots to grab some things that you would consider useless or wastes before... and I think either of these are acceptable perks to take w/ the cap increase, and even before that for certain builds.
But to answer the TC, look in your PipBoy in the Notes tab, there should be one linked to the chosen perk that details where to go.
On topic: http://fallout.wikia.com/wiki/Regulator_HQ
I think Contract Killer is a wasted perk but I don't think Lawbringer is all that bad. You always have to kill a crap-load of Raiders and various other rabble so might as well get a few extra caps for it (if you have the levels to spare that is). I just wish that CK or LB were quest perks instead of level perks.
I just wanted to point out that Contract Killer is not as useless as it might seem, because if you have evil karma, the regulators will show up every now and then, which should yield you a couple of ears every once in a while. But, yeah, Lawbringer is the better of the two.