Get a tweezers ans use something to pin the head down gently. Pull the ticks off one by one, giving the snake breaks in between, ans rinse the head with warm water.
arter snakes are pretty easy to control, if you don't mind them squirting poop all over you..
I wouldnt use tweezers. Id use a damp cotton ear swab. They get caught up nicely and no chance of hurting the snake.