brew install fastlane

1. ./install ~/somedir
2. ~/somedir/bin/fastlane

Any changes to the bundle_env, fastlane, or install will require a new release/tag and an update to the fastlane.rb formula in https://github.com/Homebrew/homebrew-core.

1. Create release/tag in GitHub
2. Download the .tar.gz
3. Get the sha256 of the .tar.gz with openssl dgst -sha256 <file>
4. Update the fastlane.rb formula in https://github.com/Homebrew/homebrew-core and open a PR
   1. Update url
   2. Update sha256
   3. Update revision (if needed)