Here's how I hooked up the PAC SWI-PS to a Pioneer AVIC-F700BT, in a 2009 Elantra GT Sport (Canadian):
In the green harness pictured below (hyundai connector # M54-D), pins 5 and 6 are the ones used for the steering wheel interface (which is a resistor network, schematic here: http://hmaservice.com/data/Passenger/HY/HM...hdsd9961cn.svg) used. Pin 6 (black) needs to be connected to ground, and Pin 5 (Green) should go to the white wire on the PAC SWI-PS.
The red and black wires (power) of the SWI-PS should be hooked up to accessory power and ground, respectively, and no other wires are used. Do not cut either of the loop wires on the SWI-PS.
The SWI-PS should be programmed for mode 8, and otherwise just follow the programming instructions that come with it.