If you happen to have an assortment of suitable NPN transistors laying around (who doesn't), you could tie the collector and base together, and then use that connection as the anode and the emitter as the cathode.
Well, that's not really a good idea... Modern NPN power transistors won't take too much base current. Better to use two power schottky diodes.
Patrick del Castillo
President, Principle Engineer
Castle Creations