I have an aftermarket stereo and was looking into something like this.. I was told my my stereo guys that theres a device that would work but it was gonna cost me around $200, which IMO is too much cause I can easily just reach my headunit, but yeah would still ove the steering controlls.. Could be the same thing as in the ebay link I dunno.. I remember reading on here, someone fitted there headunit but didnt hard wire it in, but used the AUX somehow when fitting it. When he wanted to listen to the HU he chucked it in AUX mode and it played, therefore still retaining the steering controls.. Do a search, could be your answer.. I think his username is Azid_rush or something like that...