Its pretty simple actually. I made my own tool that accepts dremel bits, use high speed steel or carbide bits, basically a knurled aluminum pen with a sharp point instead of ink. Turns out you can buy one that probably is better than mine. http://www.buy.com/p.../213586231.html
To get the fine lines and consistent shallow depth you must do it by hand, no powered rotary tools. It only works on very thin anodized finishes or on bare aluminum. Attempting it on a robust, quality anodizing takes 10x as long, will wear out your bit fast and is just not worth it.