creating settings of index using elastic4s

I have some class:

class SomeClass(val client: ElasticClient, val config: Config, val configName: String)(implicit val ec: ExecutionContext)
  extends ElasticSearchRepositoryWrapper[AnotherClass]{
    override def mapping: Option[MappingDefinition] = Some(
      properties(
        KeywordField("id"),
        TextField("name").fielddata(true).analyzer("ngram_analyzer"),
        KeywordField("lang"),
        BasicField("order", "long"),
        ...
       )
    )

I'm creating an index with repository.createIndexIfNotExists() using this mapping.
Now I must create ngram_analyzer in my index settings:

  "settings": {
    "index": {
      "analysis": {
        "analyzer": {
          "ngram_analyzer": {
            "filter": [
              "lowercase"
            ],
            "tokenizer": "my_tokenizer"
          }
        },
        "tokenizer": {
          "my_tokenizer": {
            "token_chars": [
              "letter",
              "digit"
            ],
            "min_gram": "3",
            "type": "ngram",
            "max_gram": "3"
          }
        }
      }
    }

How can I do that using elastic4s?