Strategy for Creating Fork of Android on GitHub

I'm trying to create a fairly low-level change in Android source -- changing the package manger. I want to get the whole source using the repo tool described in source.android.com. I have a fork of the platform_frameworks_base project on github.

So, the question is how do I go about getting my platform_frameworks_base instead of the one provided by Android. I just want to be able to clone my own fork, create a branch in there and then push it in my own github. I can worry about pull requests 开发者_JS百科to the main repo later.

Any help on the strategy/method of doing this?

p.s. My "workflow" is aimed to be similar to this: http://appanalysis.org/download.html

probably a bit late :) , but for the records, you might be want to take a look into this http://www.primianotucci.com/blog/fork-android-on-github