From Mac OS X System Preferences panel open the Displays applet
Ensure you display is set to the Native resolution (LCD's should always be set to the native resolution otherwise images will appear soft)
Ensure Colors is set to Millions
Set the Brightness slider to your preferred value (the Apple default is approximately 60%, although a slightly brighter level might be necessary on aging displays).
Choose the Color tab
Search the list of Display Profiles for one that matches your display and select it. In truth this step shouldn't be required since the calibration utility automatically picks up the necessary data from the display via the DVI/ADC connector.