Kerosene. Then the above-mentioned shower cap. Better than mayo. You'll need a louse comb (extra fine teeth) for the nits. Never mind electric - you'll get one at most drug stores. Learned this from the old wives in Glasgow when the whole primary school got 'em. Worked fine.

Try to treat it as you would the flu - "these are the steps you take," etc. so as not to rattle the child too much.

Learn to sing "THE LOUSY MINER" or other appropriate songs.

Enjoy

(You can also just ask your pharmacist what the latest shampoo thing is.)