I installed Babel CLI (version 6) using npm install --global babel-cli. I then install react preset using npm install --global babel-preset-react.
npm install --global babel-cli
npm install --global babel-preset-react
You can specify the absolute (or relative) path to the preset you are trying to use, e.g:
babel --presets /usr/local/lib/node_modules/babel-preset-react --watch jsx/ --out-dir js/