First add a custom resolver to your project/plugins.sbt file.

resolvers += 
  Resolver.url(
    "bintray-plugins", 
    url("https://dl.bintray.com/resisttheurge/sbt-plugins/")
  )(Resolver.ivyStylePatterns)

Then declare a dependency on the plugin in your project/plugins.sbt file.

addSbtPlugin("io.zastoupil" % "sbt-antlr-plugin" % "0.2.0")

Then enable the plugin in your built.sbt file

enablePlugins(AntlrPlugin)

Once the plugin has been added to your project, you can run the antlr task from the command line. Navigate to your project's root directory and enter the following lines:

> sbt antlr

Currently, there is no output to signify success or failure outside of antlr's own reporting mechanisms. This will change in future releases.

Integration with sbt compilation is optional. If you want to have the sources generated by the antlr task be available during sbt compilation, you have to declare the antlr task as a dependency of the sbt compile task in your build.sbt file.

compile in Compile <<= (compile in Compile).dependsOn(antlr)

Additionally, you have to declare the antlr output directory as a managed source directory for its contents to be available to the sbt compile task in your build.sbt file.

managedSourceDirectories in Compile += antlrBaseOutputDirectory.value

When using an IDE that is capable of reading sbt projects, it is also recommended that you declare the antlr source directory as an unmanaged source directory in your build.sbt file.

unmanagedSourceDirectories in Compile += antlrSourceDirectory.value

While this does not impact the execution of the plugin, it does allow your IDE of choice to recognize the antlr source directory as a source directory.