This will probably be the final piece of the explosiveness topic for now. It's taken much longer to put out to you all than I had planned.
Being explosive with footwork is something that few arts seem to address as a whole. Yet, there are a few arts out there which do address footwork as being of importance. Often the methods outlined for teaching footwork though are devoid of any discussion of becoming explosive and focus more on patterns of movement. In pencak silat and escrima for instance, there is a focus on langkah.
In many styles, there are a plethora of langkah to learn and in other styles there are but a few. Still in other styles there may even be pancar or platforms for the pesilat to learn more about footwork. These are all good and necessary to learn and can truly help your pencak silat but they often still lack the element of understanding that leads to explosiveness.
One of the primary methods of explosive footwork within the context of Pencak Silat Pertempuran is to put energy into your feet to propel you. You can do this in a couple of primary ways. For instance, stomping your feet is a basic method which can get your body moving quickly and can be combined with the next method rather than using it in isolation. One aspect to this method that can also be used is the ability to fall or use gravity to add to the stomping. It can appear to be a quick leaning forward in which the foot is not all that apparantly involved, or it can clearly incorporate the movement of the foot. It is situational and depends on the distance that needs to be covered however, either version tend to set you in motion by the same basic principle of movement described in the following version.
A second method might be to imagine yourself a sprinter preparing to start a race. Most of us have seen how a sprinter does this and few sprinters vary from this method because it sets your body up to be explosive and to propel you forward. By simply moving your lead foot backward and keeping your heel raised you set your body in motion forward.
With a little practice you can learn to combine both the first and the second method in conjunction with each other to create a good explosive foot entry.