The point is though that whatever final tweaks may or may not be necessary, you get to that point a whole lot quicker. And personally, I put a whole lot more confidence in what you have at that point, based on measurements, than what you would have at that point, based on eyeballing and subjective judgment.
It isn't all that hard but it does require some degree of eyeballing. This is because 10nm spectros can read colors from spikey monitor illuminants inaccurately but also people with normal color vision also vary. Each of us has our own color matching functions but, unfortunately, there is no way outside of a fairly sophisticated lab, to find out what they are. So we use the original CIE 1931 2 degree ones. These work well enough for most purposes but can and do provide inconsistent results with different monitor back illuminant sources. If you set an LED monitor and a CFL monitor to exactly the same xy coordinates and cd/m2 luminance they will often look different. Worse, some people will see bigger or no differences than others due to individual variation.
So here is what I do. It is very slightly different from what Andrew does but quite close.
1. Start with a good profile of a paper that is OB free.
2. Illuminate that paper on your hard proof viewing platform at an angle, preferably close to 45 degrees but always in such a way to avoid specular reflections from the surface. The brightness level from the paper is up to you but needs to be slightly below what you expect to run the monitor at.
3. Measure the xy coodinates of the illuminated paper.
4. Now profile the monitor for the same XY coordinates and a luminance value about 25 % higher than the paper's luminance. This will be changed later. It's needed so you can adjust luminance and color to the paper without clipping a channel at 255.
5. Open a new image in "white" in Photoshop. Select soft proof and Absolute Colorimetric mode in view proof.
6. Using curves or another preferred tool, drag each line (not a point within the line) down until the monitor's luminance, saturation, and hue match the illuminated blank paper on the hard proof viewing stand.
7. Once you have a match, reset soft proof so you have a normal, non-proof view but don't change any values in the now altered "white" image. Read the xy coordinates and Luminance of the monitor's display of this image.
8. Now use those values to create a new monitor profile. That is the final profile you will use.
That process will adjust for individual variations in color response as well as instrument variation and your soft proofing will match your hard proof (make sure you select view paper white). Additionally, they will match different papers as some have slightly different hues and reflectance. No need to change for different papers.