conditional compilation flags in odl file

What is equivalent of #ifdef ... #endif flags in .odl files? Is it possible that in odl file, we shall have interface methods which are compiled conditionally ?

e.g.

interface {

methods:
   HRESULT func1([in] inputvar, [out] outvar);
   HRESULT func2([in] inputvar, [out] outvar);
   
   #ifdef THIRDPARTYDLL
   HRESULT func11([in] inputvar, [out] outvar);
   HRESULT func21([in] inputvar, [out] outvar);
   #endif
}

I am using a third-party library for which I have limited run-time and developer licenses. Some of the interface methods are in direct support of library methods.

On some machines where I have license installed, I want to compile with flag on and on other machines, I want to compile with flag off.

How this can be achieved? Also, it is possible to use a flag which defined in source files, in IDL file? In visual studio, there are facilities for defining pre-processor in project. But set of preprocessors for C/C++ source files and for MIDL files is different? can they be shared or can they be inherited from some common place?

Tags: C++, Visual C++ 10.0, Win32