First thing -- unlike the Slug, the SheevaPlug is almost impossible to permanently brick. It is just a matter of how much effort it will take to unbrick it. As long as the bootloader is still intact, all the kernel stuff is relatively easy. You will probably find you will need to get to know the guts of the Plug much more closely than the Slug. Often, you may need to modify a list of instructions to fit your needs.
If you look through the wiki and these forum pages (for about 3 to 4 days), you will find about 3 to 4 different ways to upgrade the kernel. They might all work fine for you, or you might try two or three that will fail before you finally find the one that works. Patience and determination are needed.
With that said, before you even touch the kernel, I would recommend you first upgrade U-Boot. The following page worked well and easily for me:http://www.cyrius.com/debian/kirkwood/sheevaplug/uboot-upgrade.html
However, I would make one changes to the USB method:
fatload usb 0:1 0x0800000 uboot.bin
nand erase 0x0 0xa0000
0x0800000 0x0 0xa0000
Using write.e deals with any error blocks encountered.
About the SheevaPlug_Installer page -- some of the comments about the "latest" SheevaPlugs were in error:
- Some of the Plugs shipped in the U.S. (maybe elsewhere) in December 2010 (and after?) use the older 1.2 GHz cpu with the new power supplies. (Still replaced my with an external.)
- Those same Plugs are using the older VID/PID.
- The comment about the partition sizes is an error. In U-Boot, do the command printenv. If you have something like mtdparts=. . .0x400000@0x100000(uImage). . . , then you have no problem with those sizes.
In fact, it seems like small errors exist in most of the pages and documentation you might find (that happens when the hardware keeps changing). Another reason to try to understand what the instructions are trying to do before marching into them blindly.
The other page you listed: http://plugcomputer.org/plugforum/index.php?topic=3680.0
does, in fact, install the 2.6.36 kernel, and modules. However, it does not change the file system (will leave Ubuntu).
You may save yourself some time if you first decide which distribution you want to use, and where you want your root file system.
I found these two pages to be helpful when deciding how to add a new kernel:http://www.plugcomputer.org/plugwiki/index.php/Install_Prebuilt_Kernels_From_sheeva.with-linux.comhttp://www.plugcomputer.org/plugwiki/index.php/Installing_Debian_To_Flash