There is no way to execute Workflow code when using the Excel Add-in. The Excel Add-in uses the OTA API for ALM to complete its tasks. This circumvents the Workflow code, which applies only to the UI.
You might be able to modify the Excel Add-in macro. I've never tried that. But then somehow you would have to get the modifications deployed to all the systems.
You might be able to modify the Excel Add-in macro. I've never tried that. But then somehow you would have to get the modifications deployed to all the systems.