How to call GAMS from Excel using VSTO?

VSTO = Visual Studio Tools for Office (see http://msdn.microsoft.com/en-us/office/aa905533.aspx). This allows you to develop .NET code for use with Office applications. Basically newer versions of Office both host VBA and .NET. VBA code is stored embedded in the .xls file, while .Net is maintained outside the spreadsheet. MS Visual Studio has excellent tools to develop, debug and deploy VSTO based applications. The VBA code presented in http://www.amsterdamoptimization.com/packaging.html can be ported to .NET/VSTO without much problem.