download linux kernel 2.6.28 tarball. you can use apt-get source kernel-power or kernel.org website. Then you will have tarball - unpack it - it will unpack into subfolder. Then move all files from this subfolder to kernel-power/kernel-power-2.6.28

I did not used scratchbox - but it must work. It is same as madde - it use dpkg-buildpackage which is same on all debian system.