Can you not add your own custom script to a Toolbar button?
I've read all the documentation, and is it correct to say that the customization of the toolbar itself, is only to mix and match existing tools from other tool bars? I've written code in .js to auto-generate/update an excel file that runs our data driven tests. It basically reads all the TestCases we have, and strips out the individual test cases and populates the excel file, along with where each test excel data corresponding path it maps to. This made more sense to initiate it on the fly, once the number of tests started growing, and forgetting to update the file everytime we completed a new test case.
If there's no way to do this, how would you say, is the best way to initiate this process?
Look into creating it as a script extension. I'd suggest doing it as a design-time action.
See https://support.smartbear.com/testcomplete/docs/working-with/extending/script/about.html
