Hi A.,
I am a JIn Shin Jyutsu practitioner. It is a form of Acupressure that can do magic for the ears in the airplane. All you have to do to open the energy to the ears is to hold the little fingers. Your daughter can do this for herself by holding them one at a time or by putting the pad of the thumb over the little fingernail, forming a circle. Or you can hold both little fingers for her. There is no special technique. Just wrap your hand around her little finger. I would hold both of them for a couple minutes before you get on the plane, then before and during take off and landing. You cannot overdo it, so don't worry about holding them too long.
If she has any worry about the travel, or for your own worry, you can hold the thumbs. That helps release the energy related to worry. Have a great trip!
T.