Installation is easy: just place the Ableton Project Folder where you keep your Ableton instrument patches and pull the .adg instruments into your project from the Live browser!

AfroDJMac has made an awesome walkthrough of sounds as well. You'll definitely want to explore the pack with him in the video below, as well as visit his Whistle Pack page for further description, as well as a livestream of him making part of the pack (and loads more great Ableton packs to boot!).