First, clone the Ionic-CLI repo. Then cd ionic-cli, npm link - once this is done, you should be able to use ionic from your command prompt.

Alternatively, you can run the ionic commands without installing it by running node /path/to/repo/ionic-cli/bin/ionic help.

If you plan on making modifications to the ionic-app-lib - clone that repo. Then cd ionic-app-lib, and run npm link. This should run npm install to get node_modules, then install a global link to the ionic-app-lib in your user npm directory.

Next, go back into the ionic-cli repo and run npm link ionic-app-lib. This should make your ionic-cli use the symlinked folder for ionic-app-lib.

You can verify this by changing the version for ionic-app-lib to something like 0.0.19-beta.0, then running ionic info to verify that version is the one that info command spits out.