There is NO harness in place. The only harness I know is in place even if the feature isn't there is the steering wheel audio remote. If you REALLY want this feature, either go aftermarket, or find a nice used EX Luxury Sedona that has it. The EXs, especially 2006-08 models can be found relatively cheap.
My Garage has: 2006 Sedona EX 3.8L, Loaded, 203k miles----2006 Sedona LX 3.8L, Convenience Pkg, 240k miles----2007 Optima EX 2.4L, Loaded, 84k miles----2007 Rondo LX 2.4L, Convenience Pkg, 51k miles----2009 Amanti 3.8L, Loaded, 58k miles