C# DLL Controlling Firefox through C++ XPCOM

I need a Firefox extension and a XPCOM C++ component to enable the following C# DLL methods.. private string GetInputFieldValue(string iframeId, string fieldId) { ? // Implement this.? It should return the value of the input field on the main web page (or in the iframe if the iframeId > 0). } private void SetInputFieldValue(string iframeId, string fieldId, string fieldValue) { ? // Implement this.? It should set the value of the input field on the main web page (or in the iframe if the iframeId > 0). } private void ExecuteJs(string iframeId, string js) { ? // Implement this.? It should execute the specified javascript in the main web page (or in the iframeif the iframeId > 0). } public void DocumentCompleted(string iframeId, string Url) { ? // Call this when a page loads } public void Button1_Clicked(string iframeId) { ? // Call this when html button with id = 'button1' is clicked. } The C++ XPCOM should reference the C# DLL Project using Visual Studio 2008 preferably.