how to change the themes and icons of Android 2.2 OS?

I am Optimizing the Android 2.2 OS to make it in such a way that it can 开发者_如何学编程be ported to the tablet. Can anyone suggest me how to change the themes and icons of Android 2.2 OS.

I asked a similar question in another forum about a custom UI, and why Sense from HTC is the way it is. I was given a brief answer, but I think it applies to you too: It involves a custom UI application that overlays on top of what is pre-existing.