Start by cutting the arms off. Then accross the shoulders and down the sides. Use the seams as guides.
Next make the front and the back pieces into rectangle shapes. You can also use the arms if you open them up.
If making one small cushion from the front piece, fold in half and pin in place your applique. make sure you dont pin it to the back of the cushion
If using the front of the jumper as the front of a big cushion pin applique in place.
Ignore the cream fabric around my applique this is where i cut it from the old cushion i had made before.