We've been playing with the Steering Wheel utility too, but we haven't found it to be very practical or a way to support it for any of the cars we have tried on.
When you start the utility, it will show lots of stuff in korean. Once you click the "AUTO SCAN" button to start programming it, it will flash a message 6 different times for the 6 different possible buttons. Each time the message flashes, you want to hold down a different button on your steering wheel controls and it should set some hex letters in the text box. After going through all 6 different buttons, the values in the 6 text boxes should have different hex values in them. You should hit the Send command once you are done and this will program the hardware to remember the values of your different steering wheel controls.
Exit the program, now when you press any of the steering wheel controls, it should send a different key combination to windows. This key combination can be used in StreetDeck or any other program if you can program the keys for it.
Now all this that I just said basically assumes you have your can hooked up properly to the remote control wire on the G4. Unfortunatly, and this is the reason why we haven't released or support this utility on MP3Car, there is no standard for resistive steering wheel controls. Some cars use multiple wires, some reverse ground and power, some use the CAN bus which totally won't work. On most cars, to hook it up, you will probably have to add additional resistors. I have only gotten 2 of the 6 buttons working in my car and I’m doubtful there is anyway to get it working better with the one wire on the G4. Those 2 buttons work real well, but that’s bout it. If you really want steering wheel controls to work with the G4, you should just get an SWI-X, it works with the IR sensor on the G4 and has very good and well documented support for most cars.