Wiring a capacitive touch sensor to the Arduino?
The datasheet is available on http://www.azoteq.com - see the pinout there.

The effective operation of the IQS128 is dependent on good de-coupling at the VDDHI and VREG lines (see the reference designs)

If you have ordered 957-IQS12800100TSR you will have a proximity output on pin3.

If you have ordered 957-IQS12800000TSR then pin3 is an input (ENABLE/DISABLE). You will have to pull pin3 high in order to enable the IQS128.

See the manual for some information on the layout used on the 957-IQS128EV01.

Buying the 957-IQS128EV01 would give you a module that can be quickly wired/plugged into your design.