Paul,
I haven't tried it yet. But wouldn't you just have to create an IAC (inter-application connection) within audioMIDI setup, go to Clicks & Ports in the environment within Logic and do the cabling - and that would create the MIDI connection you would need.
Then you could assign the outputs of VE to your audio interface & loop it back into the inputs. Or use software loopback if you have the right RME interface.
You could additionally use 16 mono channels within the Soundflower application to return back to Logic. Soundflower also uses the IAC to get MIDI to it.
I'm sure there are many variations on the theme.
Like I say, I haven't tried it yet. So I don't know all the ins & outs of it (pun intended). But I bet somebody out there has.
A defacto VSL tutorial on it would be helpful. I have to believe that it was tried before release.