From Birth book - "A simple (but messy) method for treating nits is to cover your hair and scalp with a generous amount of olive oil and leave for ten minutes. Using a special fine nit comb run through your hair section by section. After each comb wipe the excess oil and any nits onto a piece of tissue or absorbent paper. Continue this until you have combed through all your hair and then wash your hair with regular shampoo. You may need to repeat this in 10 days time. Wash pillow and towels in hot water adding a few drops of tea tree oil to the water to help prevent them spreading."

Can't vouch for it's effectiveness but it can't hurt to try HTH