Sure Jen- to be honest I am not sure if it is in the manual- at least a decent description of how to do it. I read it online somewhere- but nonetheless- here are the basics. I downloaded the actual chart I used
HERE.
My setup was fairly straight forward- I taped the chart to the floor and mounted the camera on the tripod so it could focus as needed from about a 45 degree angle. The camera needs to be wide open to minimize the depth of field. I also bounced a flash to be sure the chart was well illuminated. I started the process moving the CF card back and forth from the camera to the computer looking at the results- but to be honest the D300 has such a nice LCD it works just as good viewing it in camera- just zoom in and check it out. Take a test shot and see how it looks- the cooresponding numbers in fron and behind the -0- line should be about the same point in focus. So if the 6 in fron is clear but the 6 in back is fuzzy then it is front focusing- it will need a +X adjustment.
Hit the Menu Button- select the Setup Menu- the 2nd to last item is "AF fine tune"- You will need to turn this feature ON. Then you will see it identifies what lens is attached to the camera and number it X/12- the first time will be 1/12. You go into 'Saved Value" and move it maybe 4 or 5 and save it- then take another test shot. Getting it perfect is kind of guesstimating and hit and miss. Once you get the hang of it it was taking maybe 10 minutes per lens. A nice feature that really seems to hone in the focusing.
Good luck- let me know how it goes.