To turn a .h into a .i file:

Add the relevant header part:
(example from Message.i:)

%module Message
%{
#include   "Mcommon.h"
#include   <wx/config.h>
#include   "Message.h"

// we don't want to export our functions as we don't build a shared library
#undef SWIGEXPORT
#define SWIGEXPORT(a,b) a b
%}

%import String.i


Replace:

virtual void foo() = 0;   --> virtual void foo();
void foo() const;         --> void foo();
void foo(type const &bar) --> void foo(type &bar);
type const &foo()         --> type &foo();

