Setting up the zone scale allows you to focus the camera approximately on distance, shorter focal lengths and small apertures helps even more. You only need to do this if you plan on using zone focusing, otherwise just focus and compose on the groundglass.
- Put camera on a tripod
- Open shutter, maximum apeture
- Decide on your normal orientation of the camera (grip right or left?)
- Put a mark / dot on the camera body near the frontcap. This will be your position for reading the actual zone the camera is set to.
- Focus a point representing infinity (e.g. 400-500m away) using a loupe on the groundglass.
- Put a infinity mark on the white tape on the frontcap opposite to the mark or dot you put on the body.
- Now repeat this process for closer distances, and mark the approximate distance on the frontcap.