Renoise can now load DSSI plug-ins on Linux, and there is a DSSI-VST wrapper that loads Windows VST plug-ins via Wine. Have you tried this yet?
http://dssi.sourceforge.net/download.html
Some discussion about getting it to work:
I’m not sure that it would work in exactly this way, though. On Windows, Renoise would see that your song uses the normal VST plug-in. On Linux, Renoise would see that your song uses the VST plug-in container/wrapper, but not whatever Windows VST plug-in is actually loaded within it. As far as Renoise is concerned, each plug-in would have its own unique ID and would therefore be treated as two completely different things. So you would probably need to write a Windows version of the plug-in wrapper as well, and use it to wrap your VST plug-ins no matter whether you’re working on Windows or Linux, just so that Renoise could effectively ‘see’ the same plug-in ID and therefore handle things the same way on each system.
Another alternative may be to use similar techniques as Chris Walton’s Oversampler VST, which lets you oversample the output of any other VST plug-in to improve its quality by reducing aliasing. If you have a plug-in named SomeSynth.dll, then you must make a physical copy of the oversampler’s DLL file and rename it to SomeSynth.os.dll. The oversampler then mimics all of the properties of the original plug-in and reports these to the host instead. Perhaps this same method could be used for the Linux/Windows wrapper plug-in. The problem here is that Renoise identifies VST plug-ins on Windows by their filename, so it would still be treating SomeSynth.dll and SomeSynth.os.dll as two different things. Not sure if it’s the same with Renoise for Linux, but I suppose it would be possible to figure something out here. As long as Renoise sees ‘SomeSynth’ on Windows and ‘SomeSynth’ on Linux, and both plug-ins behave in exactly the same way, then it should work.
Either way you look at it, there will have to be some kind of weird workaround in place to make this work.