diff --git a/Readme.md b/Readme.md
index b84b8ee..2badee1 100644
--- a/Readme.md
+++ b/Readme.md
@@ -11,6 +11,15 @@ directory a Python/Django app, and patches `settings.py` to parse the Heroku
 DATABASE_URL config vars. It then sets default process types to use the Django
 web server and console.
 
+External Language Pack
+----------------------
+Cutting-edge development is taking place in this repo. To use this on Heroku,
+set a `LANGUAGE_PACK_URL` config var with a fully authenticated URL to this repo:
+
+    $ heroku config:add LANGUAGE_PACK_URL=https://nzoschke:XXXXXXX@github.com/heroku/language-pack-python.git
+
+On next push, slug-compiler will use this LP instead of the built-in one.
+
 Compile Hooks
 -------------
 The PLP uses a Makefile for user-controlled hooks into slug compilation. If