steering wheel controls 2004 trailblazer

I am looking for someone who would be able to help me with information on installing steering wheel controls in a 2004 trailblazer that is not equipped with them from the factory. Here is what I am thinking; get a steering wheel that has the switches from a salvage yard or ebay and then get a clock spring (sir coil or spiralcable or whatever you may want to call it) from a similar vehicle and install them both.  Then get the steering wheel control interface from PAC or whoever....  and set it up to operate my kenwood dnx 9140 head unit.....  any help would be greatly appreciated.25msojr