http://www.usfirst.org/uploadedFiles...s-Rev-0-5a.pdf Page 4
Wire the + to the 5V, wire Vcc to ground, wire the other pin to signal.
When it's off, Vcc and signal will be connected, which pulls the value to 0 and will be a false in the code.
When it's on, + and signal will be connected, which makes value 5V and will be a true in the code.
The "resistor" you might have heard of is often including in the innards of the OI. This year's DS does not have one, so all three pins are used (and thus you shouldn't use 2 pin switches on the DS). You can learn about why here:
http://en.wikipedia.org/wiki/Pull-down_resistor