Some third-party calibration packages, most notably OptiCal from ColorVision (which we like a lot), allow you to set the white point by manually adjusting the RGB guns on monitors that offer individual gun control. If your monitor and calibration package offer this feature, use it – you’ll lose fewer levels than you would if the calibrator had to tweak the lookup tables in the video card to achieve the requested white point.

Real World Photoshop 6
David Blatner and Bruce Frasier, p. 135
Peachpit Press, 2001