You have to use Excel's scripting capbability to do this, can be done through VBscript in Windows and AppleScript on Mac.
(I'm not talking about VBA or embedding code in Excel, but using the Excel API from outside Excel).
FM has a Perform AppleScript script step on Mac, there is unfortunately no equivalent script step for VBscripts on Windows but there are many demos around that can show you have to do it.
So the real work is in writing the Excel API code.
I tried "Automator" that comes with the Mac (and we only are in a Mac environment here). That does the combination as I need it. Now I just have to look out for the right command to start external programs...