Вы можете сделать Plug-in в виде динамически подгружаемой библиотеки (DLL).

/* How to make plugin for "Advanced Script Host"?
   To use:
   Borland C++ 5.5.1 for Win32 Copyright (c) 1993, 2000 Borland
   Compile: bcc32 -WD helloworld.cpp
   Copy: helloworld.dll in your location
*/

#define  NONAMELESSUNION
#include <windows.h>

typedef 
HRESULT FAR (*LPFUNC)(HWND, VARIANTARG*, VARIANT FAR*, WORD, HRESULT);

BOOL WINAPI DllEntryPoint(HINSTANCE, DWORD fdwReason, LPVOID)
{ // Optionally: The DllEntryPoint function is an optional 
  // method of entry into a dynamic-link library (DLL).
  // If the function is used, it is called by the system 
  // when processes and threads are initialized and terminated.
  switch(fdwReason) {
  case DLL_PROCESS_ATTACH:
//       MessageBox(NULL, "I am plugin.", "Init", MB_OK);
       break;
  case DLL_PROCESS_DETACH:
//       MessageBox(NULL, "I am plugin.", "Finalize", MB_OK);
       break;
  };

  return TRUE;
};


extern "C" __declspec(dllexport) int __stdcall GetMethodsCount() {
  // You must return the count items. 
  return 1; // One methods must be added
}

HRESULT HelloWorld(HWND, VARIANTARG*, VARIANT FAR*, WORD, HRESULT);

extern "C" __declspec(dllexport) BOOL __stdcall 
GetMethod(unsigned uIndex, char FAR* FAR* ppName, 
          char FAR* FAR* ppMask, LPFUNC FAR* lp)
{ 
  if (uIndex == 0) {
      *ppName = "HelloWorld";
      // The arguments mask (you can use 'S' - string and 'I' - integer)
      // For example: "ISS"
      *ppMask = "S";
      *lp = HelloWorld;
      return TRUE;
  };
  return FALSE;
};


HRESULT HelloWorld(HWND hwnd, VARIANTARG* pArg, VARIANT FAR* pRes, 
                   WORD word, HRESULT hr) {
  if (FAILED(hr)) return hr; // the check arguments mask
  // You can check the types call
  // DISPATCH_METHOD 
  // DISPATCH_PROPERTYGET
  // DISPATCH_PROPERTYPUT
  // DISPATCH_PROPERTYPUTREF
//     if (word != DISPATCH_METHOD) return DISP_E_MEMBERNOTFOUND;

  // How to get the integer value?
  //   int i = (int)pArg[0].n1.n2.n3.lVal;
  // How to get the string value?
     BSTR bstr = pArg[0].n1.n2.n3.bstrVal;

  // How to convert bstr to char*?
     unsigned uLength = wcslen(bstr);
     char *sz = (char *)calloc(uLength + 1, sizeof(char)); 
     WideCharToMultiByte(CP_ACP, 0, bstr, uLength, 
                         sz, uLength, NULL, NULL);
     sz[uLength] = '\0';

  // How to return the integer value?
     pRes->n1.n2.vt = VT_I4;
     pRes->n1.n2.n3.lVal = (LONG)MessageBox(hwnd, sz, "Title", MB_OK);
     free(sz);

  // How to return the string value?
  // pRes->n1.n2.vt = VT_BSTR;
  // pRes->n1.n2.n3.bstrVal = SysAllocString(L"Hello World!!!");

  // If You to use the shell event (callback function)
  // You can call event (callback function with one argument)
     LONG oneArg = 500;

     OLECHAR FAR *pScriptFunction = L"Your_Event";
     SendMessage(hwnd, WM_USER + 1, (WPARAM)pScriptFunction, 
                                    (LPARAM)oneArg);

  return S_OK;
};

// JScript syntax plugin.w_js
var id_lib = System.LoadLibrary("C:\\helloworld.dll");
var conn = Plugins.ConnectPluginsLibrary(id_lib);
var text = Window.FormatMessage(conn);


Window.TextOut(1, 50, 50, "id: " + id_lib);
Window.TextOut(1, 50, 70, "connect: " + conn);
Window.TextOut(1, 50, 90, text);
Window.UpdateWindow();

answer=Plugins.HelloWorld("The advanced script host plugin method");
Window.TextOut(1, 50, 110, "answer: " + answer);
Window.UpdateWindow();

function Event_Finalize(code) {
  System.FreeLibrary(id_lib);
};

function Your_Event(param) {
  Window.MessageBox("Your_Event", "param: " + param, 64);
};

'VBScript syntax plugin.w_vbs
id_lib = System.LoadLibrary("helloworld.dll")
conn = Plugins.ConnectPluginsLibrary(id_lib)
text = Window.FormatMessage(conn)

Window.TextOut 1, 50, 50, "id: " & id_lib
Window.TextOut 1, 50, 70, "connect: " & conn
Window.TextOut 1, 50, 90, text
Window.UpdateWindow

answer=Plugins.HelloWorld("The advanced script host plugin method")
Window.TextOut 1, 50, 110, "answer: " & answer
Window.UpdateWindow

Function Event_Finalize(code) 
  System.FreeLibrary id_lib
End Function

Function Your_Event(param) 
  Window.MessageBox "Your_Event", "param: " & param, 64
End Function