Ya know, Open Source seems to be more about kicking something out the door and letting people play with it. I think I'll just hand code each parse tree transformation and save the transformation language till the next version. It seems I don't really understand how to do something until I've already written it anyway. And then it needs doing again.
I think I'll refactor genpy into a subclass of the Python Compiler Visitor, and then hand-code up the tree transformations. I would really like to get a minimal prototype out the door SOON.