use lice shampoo and bathe his hair in it then brush through it with a lice comb just like a normal shower so he isn't suspicious of you giving him a bath just use lice killing shampoo it's alot better with just a shower or bath, good luck and hope you get rid of it soon..
other tips:
wash all clothes and stuffed animal toys-they could have the lice on them and spray his room with lysol disinfecting spray.
And If you want some effective natural things for removing your head lice so you can check it out at