I downloaded the android sources using repo. It says repo is initialized to a directory and thats where the folders get downloaded. Now I have another local_manifest.xml file which I want to use with repo sync to fetch another directory. How do I use this new manifest file to fetch the directories to my repository?
If the file name is really local_manifest.xml, you most probably want to add it to your build instead of building using just it. If that is the case, then simply place it in .repo:
cp /whereever/local_manifest.xml .repo/local_manifest.xml repo sync
The repo tool essentially concatenates manifest.xml and local_manifest.xml.
For more information, see http://www.androidenea.com/2010/06/using-localmanifestxml-file-in-repo-to.html