Need help with C extension module

[chris]

This is my first attempt at undertaking a C extension module.  I want
to wrap an existing C library so I can call the functions from Python.
There are only two functions I'm interested in calling.  I did mess
with Pyrex a bit and Swig, to no avail, so I turned to doing it by
hand.  Using the example in Programming Python, I did get the easier of
the two functions working--only takes a string parameter.  I'm stuck
now on the other function and not sure how to wrap it, because it
involves some structs.  Here's a simplified version of the C:

struct In
{
  int x;
  char* s;
  ... (only primitive data types)
};

struct Out
{
  int y;
  char* s;
  ... (only primitive data types)
};

Out* func(In* x, Out* y);

So the function takes pointers to the two structs, and fills out the
output struct and also returns the pointer to it.  I would envision the
Python looking like

in = In()
in.y = 1
in.s = "abc"
...

out = func(in)

maybe?  Just no idea how to deal with the structs in the C extension
module code.

Any tips appreciated.

Thanks,
Chris