I'm using the 3.5.4.1-rc2-T2 Hentges ROM and I tried upgrading to the 3.5.4.2-rc2 kernel but it complained on bootup
You need to edit or remove /etc/init.d/checkversion
to remove that warning... 'before' you flash and boot a different kernel.
You should also install the 'matching' kernel modules for your new kernel.
Greg