Panko, the Japanese breadcrumbs that make super-crispy breading, are made with special dough and an electromagnetic cooking process–not something recreatable at home. Chowhounds offer a couple of alternatives if you’re stuck panko-less and crave crispiness:
chameleonz approximates panko’s texture by trimming the crusts from good whole-loaf white bread, slicing it, letting the slices sit uncovered for an hour, and running them through the shredding disc on a food processor. Then he spreads the crumbs on a baking sheet and put in the oven with the heat off until they dry out.
shanagain gives Rice Krispies a whirl in the food processor. Seriously, she says, they do the trick.