[BrianG]

It's hard to tell from the pic, but the 5 pins are probably as follows: 2 for the LED, and 3 for the SPDT switch; common, normally open (NO), and normally closed (NC).

If I were a betting man, I would say the outermost terminal marked + is the LED anode, the opposite outermost terminal would be the cathode (-). Use an multimeter to verify. Depending on the amount of voltage the ohmmeter outputs in resistance mode, it may dimly light up the LED (when hooked right).

That leaves the three terminals in the middle. Usually, the center pin the common connection, one of the outer pins will be either NO or NC. The other pin would be the opposite; NC or NO. So, hook a meter on the middle and one of the other pins and measure the resistance. If it's infinite, its the NO connection. If so, turning the switch on should make it read 0 ohms (or close to it). Then, do the same between the middle pin and the other pin. The results should be opposite.

Another clue is those three blank spots. I bet those would be for another three terminals for a DPDT switch.

EDIT: Oops, I didn't see the part you wrote on the bottom of your pic. So, I was right. They did this so that you could wire it however you wanted depending on your needs. If you do use it, you will need a resistor or you'll blow the LED. If you don't want to use the LED, just leave those pins disconnected; the switch will still work.