I question the need for anyone new to analoq photography to have a "personal EI." I would suggest shooting at box speed for now. It will soon become apparent whether any adjustment in speed is required. Perhaps he will need to do this later if he gets bitten by the zone system bug. Has the OP's friend even selected a film and developer?
The concept of needing a personal EI is really a holdover from the days of fixed contrast papers.
A personal EI is not just a holdover from the past. ISO's are established by film manufacturers based on fresh film in a very specific developer, and very specific development techniques. The film we buy is never fresh because it has passed through several warehouses, and been transported several times prior to sitting on the dealer's shelf for who knows how long. . Since the EI is based on shadow density there is a rather simple method for getting close with use of a four sheets of film. I actually make this test with one sheet of film which is far easier to do than it is to put into writing. The test ios totally visual requiring no special instrumentation.
1. On a sunny day set up the camera by a north facing wall. Focus on infinity then swing the camera to face the wall.
2. Insert a holder loaded with film.
3. With the meter set at the mfg ISO. Take a reading of the wall. This will give you a Zone V rendering of the wall. Set the lens and shutter to give a Zone I reading - in other words 4 stops less light than Zone V.
4. Withdraw the slide ½ way. Make the exposure.
5. For the second exposure give 1/3 stop more light, again with the slide partially removed.
6. For the third exposure give 2/3 stop more light in the same manner.
7. For the fourth exposure give one stop more light than exposure number 1.
8. Develop each sheet normally.
9. Assuming one is using a film rated at ISO 100, this will produce negatives with EIs of 100, 80, 64, and 50.
10. The negative which just shows tonality is exposed at the EI appropriate for your procedures.