Even with the proper tools, grating a lemon can be a tricky task. It is all too easy to accidentally grate your knuckles or fingertips along with the lemon, and you must be careful to avoid grating into the extremely bitter white pith just below the yellow peel. Without a grater, the process will probably take slightly longer, as it will involve extra steps. However, the result will be almost indistinguishable from true grated lemon peel.
Scrub and rinse the lemon thoroughly. This is important because you will be using the very outer layer of the peel, so you will consume any pesticides, dust or other contaminants on the peel if you do not clean it thoroughly.
Slice off the very outer layer of the lemon's peel with a sharp paring knife. You can either cut off strips of the lemon or attempt to peel it in one round spiral, as with an apple. Examine the peel you have cut off to ensure that it does not have any white pith attached. If you find any, carefully trim it off with the paring knife.
Place the lemon peel on a cutting board. Chop it up finely using a large knife until the pieces reach the size you wish.
You can use either a citrus zester or a microplane in place of a regular grater to remove a lemon's skin.