My tool uses a different method than previous tools.  Other installers put loose files in the data directory which the client uses to override.  Mine uses packaged data files that the client natively reads, but requires a change to your launcher.  The "Add to Launcher" option automates that, or you can just add

-assetpath assets\mods

To your custom launch parameters.

In Tequila that's here:

And in HC Launcher that's here:

Currently the program is not digitally signed, so when you first run it (and after any updates to the program) you will have to allow the application to run if you have Windows Smart Screen enabled, code signing certs are expensive, and are difficult to get approved for, depending on how popular the tool gets I will try to get a code signing cert to stop the annoying dialog when you run it.

If you see the below popup when running the CityModInstaller program click the "More Info" link then click "Run Anyway"