the 7805ck is actually a regular 7805 with a TO-3 case, and can be used (with adequate heat sinking) up to about 2A. the pins are in and out, and the case is ground.
i'll take a whack at doing a current boosted regulator schematic (it's not in the data sheet, so i'm doing it from memory...)
forgive the crude paint image, but you see how it works. the 7805 has it's ground lifted 0.7Vdc by the 1N4004, which compensates for the 0.7V drop across the B-E junction of the transistor resulting in a regulated +5V at the emitter. your load is the "emitter resistor". the transistor should be heat sinked, and remember the transistor tab is at +16V, NOT ground, so the heat sink should be isolated from ground.
i made one error in the drawing, and it is that the input to the circuit should be connected to the +16V rail, before the 7812, not to the output of the 7812.