Mine

loadSuperClass('kernelpackage')
class Kernel(KernelPackageRecipe):
    name = 'kernel'
    version = '2.6.20'
    #version = '2.6.20.1'

    def unpack(r):
        r.macros.mmversion = '2.6.20-mm2'
        r.macros.mmupver = r.macros.mmversion.split('-')[0]
        r.addPatch('http://kernel.org/pub/linux/kernel/people/akpm/patches/%(major_version)s/%(mmupver)s/%(mmversion)s/%(mmversion)s.bz2')
        #r.addPatch('ftp://ftp.fsl.cs.sunysb.edu/pub/unionfs/unionfs-2.x/linux-2.6.20-u1.diff.gz')

    # for this mm kernel, we don't really care what the other options are, so
    # long as we get unionfs, so we override configure
    def configure(r):
        r.extraSource(addConfigs(r))
        r.Make('oldconfig < /dev/null')
        r.Replace('# CONFIG_UNION_FS is not set',
            'CONFIG_UNION_FS=m\nCONFIG_UNION_FS_XATTR=y', '.config')