Wraps the 'next' version of npm v3 as an executable npm3.
Allows you to use npm v3 alongside whatever other version of npm you currently have installed.
npm install -g npm3
Remember to run this semi-regularly to get the latest version of npm v3.
Make sure you understand what's changing in npm v3 by reading the excellent Release Notes.
The npm3 executable behaves exactly like npm:
> npm3 -v
3.2.2
> npm3 install
> npm3 search
# etc
MIT