brew install tdewolff/tap/<formula>
Or brew tap tdewolff/tap and then brew install <formula>.
Or install via URL (which will not receive updates):
brew install https://raw.githubusercontent.com/tdewolff/homebrew-tap/master/Formula/<formula>.rb
To install minify, run:
brew install tdewolff/tap/minify
brew help, man brew or check Homebrew's documentation.