If you want to run a macro after data has been merged into the final Excel document, open your template in Edit mode (File>Edit Template...) and create the macro under the name: RunAfterMerge.
It will then automatically run after Excel Quote-Invoice Maker has finished creating the new document (but it won't run automatically when you open the template in Edit mode).
NOTE: this is valid for v. 7.3.0.1 and up only. If you are not using an earlier version, you can get the update from the Help>Check for update menu.