It looks like a variable resistor with a built in switch, either that or a digital encoder.
if it's the resistor then the two outside connections should be for the on-off switch (this could be good) the three center connections are the pot the center one is the wiper, connect #3 and 4 together then use #2 and 3 for your resistor.
there is no + or - polarity for this device...
No, that one is one of those "combined tracks" potentiometers that you can find in CD/DVD players ..... they usually have a common ground pin, 2 "input" pins, and 2 "wipers" pins ..... you can still use it as normal, single potentiometer, tracking what is the wiper and other from one track, and ignoring the remaining 2 pins.
EDIT: I've found some i have around and checked the pins, if this can help you:
Mine are all 2 x 50 Kohm, except one that is 2 x 100 Kohm ..... keeping it in front of you horizontally, with the wheel at top and the pins facing you, from left to right you have: