More than a couple years ago, there was a guy who was making a data transfer interface from an old Compaq iPaq to a 2610 or 2720. A friend had one of his rigs and intended to use it on the TAT.
But short of that, I've not seen anything else that would hook up directly short of a computer.
I do have a USB to serial adapter (somewhere) that I could use with my laptop and the old III+ that I had years ago. So, if you were able to get your info from your phone to a laptop or netbook with Mapsource on a thumb drive, and had the means to go from that to the GPS V, it might be doable.