When I did force feedings I used a credit card to get the mouth open then used a smooth toothpick end to gently push the worm piece down the throat.
I don't assist feed any snakes especially neonates. I believe there is more going on with the snake then just not eating. My success with force feeding was 0%. The snake may have started eating on its own but within months died quickly for no known reason.
I bow to nature and understand not every snake in a litter is meant to live. I used to struggle with the death of these young snakes, thinking I had done something wrong or wasn't providing what was needed.
"The strong shall survive" and "Nature does know best" in most situations.
I still feel bad when I lose these little ones but have a much clearer understanding of why.