Digital BW, The Print

Clayton's approach is certainly viable and I'm not posting this as a
counter to it, only a clarification of the issue.
The only way to properly implement color management with the ABW
driver is with a single channel icc profile. A color profile, one we
typically associate with color management, would convert your gray
file to RGB on the fly and I don't believe the ABW driver would deal
with it.
If you wanted to pursue it, Roy's Create ICC that comes with QTR would
be the best approach but dependent on a spectro. The other approach
would be the time tested and luddite way of making a custom B&W dot
gain curve by eye, and saving it out as an icc profile.
Tyler
www.custom-digital.com