You can use it as a "null" meter. You first have to get a good print through trial and error. You then (with the enlarging attachment) meter the projected image on the easel, best to pick a repeatable tone, such as a skin tone. Note what number the needle is on.
Now, take another negative, meter a similar tone, varying the aperture on the enlarger lens to get the same reading off the exposure meeter. Bingo, should make a keeper print at the same seconds of exposure. If your negatives vary all over the place in contrast, then this method won't work too well.