[plt-scheme] Questions about modules, compilation, namespaces, planet and ffi

It's me again, I have a new question about the ffi.
How do I manage unions and struct bitfields??

For example:

struct A {
  int field1 : 1;
  int field2 : 1;
  union {
     int i;
     char c[4];
  };
};

Well, I'm going to look at the sourcecode anyway, maybe I can find the
solution there.