// add a "MS Access File" option into a standard Open File dialog
public static void ExtendOpenFileCommand(this SpreadsheetControl spreadSheet)
{
IDocumentImportManagerService service = (IDocumentImportManagerService)spreadSheet.GetService(typeof(IDocumentImportManagerService));
CustomDocumentImportManagerService customService = new CustomDocumentImportManagerService(spreadSheet.Document);
spreadSheet.ReplaceService <IDocumentImportManagerService>(customService);
}