Look in the file truss/packages/mtcdt/README.txt and
truss/image/README.txt.

The ipk files needed for the upgrade should be built,
and then all the files not needed for the upgrade should
be removed, and then bitbake package-index run.

The mtcdt or mtcap directory can be copied into the
truss/packages/mtcdt or mtcap directory.  If mtcap
is used, the install.sh script will need modification.

The kernel image from build/tmp/deploy/images/mtcdt
(or mtcap) can be copied into the image directory.

truss could be renamed to suit the kernel name and
version.  For instance kernel-3.12.70-r17.1.

A tar file is then created with the truss name as the
root of the tar.