One trick I use when I absolutely have no options left but to assist feed is to take a 3" x 5" index card and fold it in half, and use the folded edge (to prevent paper cuts to it's mouth) to gently separate the jaws, using the card to hold the lower jaw down. My helper then uses the tongs to place the feeder (prepped as suggested previously by wetting it) inside the mouth so that the head of the feeder is just at the beginning of the throat, at the same time removing the card.