Color Indicator in the Status Bar?

I am trying to make my status bar menu have a background color [green/yellow/red] depending on a given status. I think the Level Indicator Cell should be helpful, but how can it be put in the status bar?

A relevant blog article: http://dacc.exaptic.com/2009/02/color-status-bar-in-cocoa开发者_开发问答-with-nsindicator/

Create the NSLevelIndicator (a subclass of NSView), and use it to setView: on your NSStatusItem.