Yes. Either organic sphagnum peat moss or organic coco coir will work well. Composting requires aerobic bacteria to work. An aerobic organism survives and grows in an oxygenated environment. Oxygen is the key ingredient that allows aerobic bacteria to break down waste quickly and without odor. Mixing in either the sphagnum peat or coir breaks apart the feces to allow the aerobic bacteria to get it's oxygen. Without oxygen, anaroebic bacteria will thrive, and this will break down to compost, but at a significantly slower rate, and will produce a smell.