As the gem name suggests this is a guard extension. Make sure you get guard first.
Install the gem:
gem install guard-premailer
Add it to your Gemfile if you're using bundler (you should)
Add a basic guard setup:
guard init premailer
- Source is hosted on Github: guard-premailer
- Report issues/questions/feature requests on the Github Issue tracker for guard-premailer
Pull requests are welcome.