A stylish Hacker News extension for Chrome. HN+ for Chrome
If you want the stable release, visit the extension on the Chrome Extension Store: How to usehttps://chrome.google.com/webstore/detail/oieefcckcbbgniifdhhialgkmghahjgl
There might be a few branches of HN+ maintained at any given time, simply checkout the source code and switch to whichever branch you want to use. Open up your extensions page in Chrome, check the Developer mode button.
You'll see a bunch of options open up, select "Load unpacked extension" and browse to the folder you downloaded the source to.