Well, the good thing with I-DEAS is the ability to perform cutting with "orphan" solid forms.
I assume you have a 3D model of your product in I-DEAS. Make it a fully 3D soild orphan form.
After which you have a part to be the foam, which in most cases could be the four corners, for this example I choose.
Then create a cut into empty space of a cylinder... it is ok. After the cut is completed, go to the history, select the feature, and edit it. In the edit menu, select "replace feature" and that of the product model orphan. If successful, you will have removed the volume of the foam part.
Try it... there may be errors and problems at first, but practise make perfect. Good luck.