In case people aren't aware - you can use any language with COM bindings to script Excel/Word/PowerPoint/Adobe/etc from outside the application.

Python has pywin32. Usually I have a python prompt and Excel open side by side and highlight cells I'd like to modify in Excel and then switch to Python to run the appropriate functions.

The COM API can be used interactively (attach to an existing instance or launch the GUI) or automatically (launch an Excel instance but turn off visibility).