I've had a very quick email back from Access support (Joerg Huettner, respect!).
To export a patch using Virus A/B/C: You can use either SoundDiver:
... right-click the patch and select "Export MIDI File".
Or if you don't have SoundDiver, you can do a patch dump from the Virus itself and use any sequencer to capture the data. To do this, press the CTRL Menu button (or System Menu button for Virus C) on your Virus, navigate left or right until you see the "MIDI DUMP TX" setting, then select "SingleBuff" to get ready to dump just the current patch. Press "Record" in your software sequencer and then press "Store" on the Virus and it will send the patch data. Once recorded, save the data as a standard MIDI file.
To export a patch using TI/Snow: You can either do the same as above (export a patch manually via the System menu (via the "MIDI DUMP TX", "SingleBuff" as described above for the Virus A/B/C)).
OR you can do the following, explained by Joerg: "
With the Virus TI Control PlugIn this can be done by simply copying one of the Midi Files that reside on the hard drive under
Windows:
Access-MusicVirus TIPatches in “My Documents” folder
Mac:
/LibraryApplication Support/Access Music/Virus TI/Patches
and then renaming the copy and deleting all sounds from it in the Virus TI Control PlugIn then in its BROWSER tab. Then you can copy just one sound into such a copy of a sound bank there."
It goes without saying, back up all of your data before moving things around as I'd hate for people to accidently overwrite and lose stuff.