You can either build Baritone yourself, or download the jar from September 3 from <ahref="https://www.dropbox.com/s/vje9x3xd3eaplxu/baritone-1.0.jar?dl=0">here</a>
To build it yourself, clone and setup Baritone (instructions in main README.md). Then, build the jar. From the command line, it's `./gradlew build` (or `gradlew build` on Windows). In IntelliJ, you can just start the `build` task in the Gradle menu.
Copy the jar into place. It should be `build/libs/baritone-1.0.0.jar` in baritone. Copy it to your libraries in your Minecraft install. For example, on Mac I do `cp Documents/baritone/build/libs/baritone-1.0.0.jar Library/Application\ Support/minecraft/libraries/cabaletta/baritone/1.0.0/baritone-1.0.0.jar`. The first time you'll need to make the directory `cabaletta/baritone/1.0.0` in libraries first.
Then, we'll need to modify the Impact launch json. Open `minecraft/versions/1.12.2-Impact_4.3/1.12.2-Impact_4.3.json` or copy your existing installation and rename the version folder, json, and id in the json.
- Add the Baritone tweak class to line 7 "minecraftArguments" like so: `"minecraftArguments": " ... --tweakClass clientapi.load.ClientTweaker --tweakClass baritone.launch.BaritoneTweakerOptifine",`. You need the Optifine tweaker even though there is no Optifine involved, for reasons I don't quite understand.