I wouldn't count on it. As Nick C said, you'd need one that acts like a USB storage device, which means that you'd have to specifically buy one. Regular bluetooth adapters simply act as a bluetooth antenna, and don't have the bluetooth software stack loaded onto their internal circuits. But you do get fancier ones, which cost more. Alternatively, you could have a bluetooth system installed on the Auxiliary port of the unit, but then you might as well just go trade it for the bluetooth-enabled model. It will work out much cheaper that way.
Get one of these things and just load all your songs on there.
Otherwise, if that's not an option, get a quote for someone to install an SPDIF cable so that you can plug it straight into your phone/device.