I'm not familiar with the major, but I've owned a minor for decades and I suppose they are equal...
In room light (far from the bulb), adjust the eypiece position so the hairline looks sharp, and then fix it (screw?) so it will stay put.
Place it under the enlarger by the center of the photo (without the red safe filter, lens wide open) and focus the enlarger so the film grain is sharp.
If you want to be very exact, place a piece of photo paper under it.