Good point.

From here: ODBC is a call-level interface, not an application, network layer, or database driver.

So, if you want to use ODBC (which is probably what your existing clients are able to talk to), you'll need to build a Windows DLL and/or a Unix shared library that implements the ODBC driver calling interface, and turns that into some kind of network traffic to your virtual server.

You could take a look at OpenLink's Multi-Tier product for a commercial example of this type of solution. (In fact, you might be able to decode the network protocol they're using, which would let you reuse the existing drivers they've compiled for various platforms.)

There also seem to be some free solutions that you might be able to piggyback on, like Boeireep. Googling for "odbc driver generic network protocol" should find some more candidates.