So this mod works as any other mod: it adds a new object, in this case LATIN language.
You need to simply load it on world creation.

You can:
1) Either make your own mod and publish it. Set LATIN in any of your custom entity, and mention this mod as dependency.
2) Or use one of my mods that change default races.
3) Or copy-paste the language file in your modpack that you are developing for easier use.