How do you brief a photographer for pack shots without knowing the technique?

Bring the real pack and say which label text has to be readable. You do not need to talk about lights: if the batch is not printed, there is nothing to photograph. Mark on the label the lines the wholesaler has to be able to copy. In Madrid a mood is described and the batch code comes out cropped. The note is the pack, the lines that have to read, and which listing it is for.