Actually, I think you can't. You have to provide a set of initial landmarks from which the search will start. That's because the program implements the ASM search only and does not include any face or eye detector to find a starting point for the algorithm.
Try Stephen Milborrow ASM/AAM software, STASM. It has similar functionalities and, as I recall, includes face detection with two different algorithms for initialization. I learned a lot about ASM and AAM with it.
Hope it helps!