Dissolve Jello in boiling water. Add pineapple juice, ice cream and 7-Up. Mix thoroughly (In a blender if necessary to dissolve ice cream), and pour into a deep pan, approximately 9" square. Chill until mixture begins to set. Lay Twinkies, flat side down, in two rows of four across the top of the chilled gelatin. If the gelatin is properly chilled, it will resist the Twinkies. You will push them in and they will slowly rise. Remember you don't want them buried. Just semi-decended in the ooze. Chill until fully set and serve.