How do I get a CMYK "true black" in photoshop?

I work at a newspaper building ads. I have problems with black text in color ads coming out with ink on the CMY plates. This causes a problem when the print isn't in registration and there's CMY haze around the black text. We've recently had to eat the cost of a few ads that were ruined this way. It's partially the fault of our press operators, but if I could find out how to get "true black" in photoshop (without the CMY ink) I could fix the problem for good. Any ideas?