The boots are vintage paratrooper side-zip boots that I found at a surplus store back in the 80's. To make them look like they've been covered in marshmallow, I watered down some white airbrush paint and applied it with a brush, then wiped it away with a damp cloth. The flash is too intense in the picture and the detail is much more subtle....
Several years ago, someone scored Ernie Hudson's screen used boots and posted a few pictures. They looked pretty much the same.