Live CSS Mod Extension

The production plugin is on the Chrome Web Strore

Run it in development

In your Chrome Browser

Bring up the extensions management page by clicking the wrench ico and choosing Tools > Extensions.
If Developer mode has a + by it, click the + to add developer information to the page. The + changes to a -, and more buttons and information appear.
Click the Load unpacked extension button. A file dialog appears.
In the file dialog, navigate to the folder extension and click OK.