As a side-project to my work on WrapVTK (itself a side-project of SimVTK), I've dug deep into the VTK python wrappers to see how easy it would be to make VTK classes that aren't derived from vtkObjectBase available from python. The answer I dug out is that it wouldn’t be easy, but it wouldn’t be particularly difficult, either.
So, I'd like to announce that I’ve gone ahead and updated the VTK python wrappers so that they can wrap the special type "vtkVariant" and, potentially, dozens of other special-purpose types used by VTK. You can find the code at my VTK fork on github, http://github.com/dgobbi.
This will be an ongoing project (but hopefully not going on for too long). Things are already working much better than expected.