Jacobo is found in the Asylum in Crows Nest (explore it a bit and he will appear out of nowhere
Mycos
Mycos is in the Black Market, found underneath a trapdoor next to a thug who calls you when you get close and asks you to be discreet (you might have to mind read him)
By the way... I'd advise to leave Mycos for last because he sells some pretty decent stuff
One can only know how far he can go by going too far.
