This is so easy and so delicious. Just be sure to give yourself enough lead time if they're for a specific dinner; they need to be in the jar for at least three weeks.
Wash the lemons well. You can use any lemons, I suppose, but I always use Meyer lemons because the rinds are softers and lemons have more juice. Cut the lemons into quarters, leaving the attached only at the stem end. Pack the cuts generously with salt. Put a couple of tablespoons of salt in the bottom of a jar and pack the lemons in layers, sprinkling a thin layer of salt between each layer of lemons. Push the lemons down firmly to pack them tightly and to help express some of their juice. Add a bay leaf, or two, a few whole cloves. Cover them with water. Finish with a layer of olive oil. Cover the jar tightly. Leave at room temperature, in the dark, for at least three weeks.