As discussed in python-dev, I have started a prototype for pep 376 to define the APIs. I have changed the APIs with Phillip feedback (eg using holders)
It's located here : http://bitbucket.org/tarek/pep376
The idea would be to refine it until everyone finds it good, then update PEP 376 accordingly, then move forward with it
It's on bitbucket, so feel free to create a branch to demonstrate a change.