Since yesterday the package pybootchartgui is included in Chrome OS. Unfortunately, the download URL of that package which is accessed during the building process of the local repository (make_local_repo.sh) is wrong. Instead of http://build.chromium.org/buildbot/packages/pool/universe/p/pybootchartgui/pybootchartgui_0+r124_all.deb it has to be http://build.chromium.org/buildbot/packages/pool/main/p/pybootchartgui/pybootchartgui_0+r124_all.deb. To successfully create the local repository you have to change src/package_repo/repo_list_image.txt on line 371 accordingly.
Google released the Chrome OS source and now everybody can create his own build. But how do you get your build image file on a botable USB stick? This tutorial describes the process step by step for machines running on Windows or Linux.