Don't worry about custom curves in the D1x, it's fine in it's standard form. Set the contrast to low, turn off the in camera sharpening, and set the rear LCD to "blinkies". When you check the LCD, the dress should look white, but not have any "blinkies" showing. Add contrast, saturation, and sharpening as needed in Photoshop after the fact, and Bob's your uncle.
David Buzzard