Usually the center lead is the base, the tab is the collector. If the center lead is the base you will see <.7V with an ohmmeter to the collector and emitter from the base. If you then hook the transistor up in a common-emitter circuit, emitter grounded, collector to +5V and apply a 100k to +5V to the base, you will find that reversing the collector and emitter will result in one configuration resulting in lower collector current, this is then the reversed connection of C and E. You can use a 1K resistor from the collector to +5.