pickling new-style extension types: examples?

[Maciej Kalisiak]

I've implemented a new extension type in C, and am now attempting to make it
picklable, with little success.  Can someone point out any online examples of
doing this, or even post some code snippets?  Ideally I would want to implement
the pickling functionality in C, but will settle for a Python class wrapper
around the extension type, if necessary.  Either the __reduce__ protocol, or
using the "copy_reg" module will do.