It's /testing dir, what i don't remember is where are the exactly documentation to upgrade to it.
Found it: "The installer utilizes the 2.4.26 kernel (this still provides the best
performance on my own machines, and is also safer for partitioning
hard drives). If you want to upgrade to the 2.6.7 kernel it is also
included and the system will fully support it. See the README.initrd
file in the testing/packages/linux-2.6.7/ directory for directions on
upgrading the system to use 2.6.7 (or better yet, make it an alternate
boot choice)." <-- From RELEASE_NOTES on cd 1
And a direct link to README.initrd:
http://mirror.switch.ch/ftp/mirror/s.../README.initrd