Although I don't have a Dreamplug, I don't think the method I use for updating cbxbiker's kernels will be different on another 'plug. No guarantees however!
First I log on to the root account - I believe this is necessary to avoid privilege problems.
I then cd to the '/' directory though this is not really necessary I think.
I then download the shell script file from xilka.com (necessary because of script updates), viz:-
wget http://www.xilka.com/kernel/UPDATE-KERNEL.sh
The script file should recognise the machine type by looking at /proc/cpuinfo for non-.dtb kernels or /proc/device-tree/model for device tree kernels.
Looking at the script, I don't see any reference to the Dreamplug so I don't know if this will work. I have had to amend my script versions due to the various spellings of the machine type in the /proc/cpuinfo or /proc/device-tree/model files so it is probable that you can change the script if necessary. I have made various posts in
http://www.plugcomputer.org/plugforum/index.php?topic=6255.msg20683#new thread on this.
I then execute the shell script which goes through the motions of kernel updating, viz:-
bash UPDATE-KERNEL.sh 3.12.x
Substitute the kernel version you wish for. You will be asked whether you want the kernel loaded to nand or to your /boot directory. I don't use nand so I use the /boot (r) option. This should then download the kernel and modules with their sha1 checksums and then install the new kernel to /boot and the modules to /lib/modules/3.12.x. At this point, either a symbolic link to the new kernel or copying the new kernel to uImage will be required - there is an instruction to this effect. Typically my /boot directory looks like:-
[email protected]:/# ls -l /boot
total 9764
-rw-r--r-- 1 root root 2430244 Aug 23 12:27 kirkwood-sheevaplug-esata-3.10.9-uImage
-rw-r--r-- 1 root root 2464616 Sep 28 18:45 kirkwood-sheevaplug-esata-3.11.2-uImage
-rw-r--r-- 1 root root 2536269 Dec 5 19:56 kirkwood-sheevaplug-esata-3.12.3-uImage
drwx------ 2 root root 4096 Aug 7 2012 lost+found
-rwxr-xr-x 1 root root 2536269 Dec 5 19:56 uImage
Depending on how your /etc/fstab is set up - I normally boot from /mnt/sda1 and not from /boot so I have to copy the contents of /boot to /mnt/sda1 - that should be all that is needed. Again I don't have a Dreamplug so no guarantees.
Then I gird my loins and reboot! I havn't had to use the console port very often and if anything goes wrong, I find it easy to either remove the SDHC card or esata disk to another machine and copy the old kernel file to uImage - the old modules will still be present. If another machine is not present, I can use the console port to get into u-boot and change (setenv/editenv) the boot sequence to use the old kernel filename rather than uImage. I do not save the u-boot environment.
Not sure if this helps but Happy new year anyway!