Might be better off search the 3 series forums... there is a lot of folks over there who have done retrofits. While I can offer no solid advice, I'd suggest looking into MULF/Combo box retrofits. You might even get lucky and already have the necessary modules, they would just need to be coded to activate the USB/Bluetooth, obviously you would still need to add the USB wiring/hub/port.
I appreciate and applaud your choice of a non-optioned 1M.
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/Craig
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