You can add these essential oils to a natural shampoo, or by making a your own shampoo, hair mask, or serum. Just be sure to do a quick search to make sure you're adding the right amounts and checking for sensitivity, and as always, be sure to avoid mucous membranes.
Disclaimer: As always, use caution with essential oils. Avoid contact with mucous membranes. Not safe for direct contact with cats. Avoid the sun for 12 hours after direct contact with citrus oils. Do a skin patch test before handling essential oils to ensure there is no topical sensitivity.