if your looking just to change a theme, the icons themselves are located in the drawable hdpi folder located in the framework. If I were you I would open a couple themes side by side and swap icons in the drawable hdpi folders, then install the theme and try it out just to get an idea, 7 zip file manager and Gimp will be your most important tools but this manual I'm attaching has a list of everything. Heres a more advanced writeup that I stumbled upon on the internet, its got alot of good info. Also, look into metamorph and ninjamorph, they are free apps on the market and there are some you tube videos floating around on thier use.