Beneath the black version there is already a HOWTO for the prior Beaglebone which should be copied to the wiki: http://dev.gentoo.org/~armin76/arm/beaglebone/install.xml The HOWTO for the black version does not work for the old one.
As mentioned in the article, these steps were tested on Beaglebone Rev. C. I do not have older hardware, but I would be interested to know what did not work for you. Also, a link to the old howto is placed in the very beginning of the article for reference. If you want to copy the information from the old post to the wiki, please keep the articles separate to avoid confusion.
The old howto has several issues: 1) It does not elaborate on setting up a crossdev environment. Following the instructions as outlined will not work unless you have previously setup a crossdev environment, as it requires a different /etc/portage structure than a default installation. 2) There is an oversight in the old article. The author emerges a new version of u-boot-tools (which has the needed utility mkimage), performs all of these modifications to an old u-boot source tree, then utilizes the newer version of u-boot pulled in from u-boot-tools anyway when compiling the kernel. 3) You do not need to apply any custom patches to a newer versions of u-boot. The u-boot version mentioned is from 2013, and the github repo for the u-boot patches mentioned has not been modified for 2 years. 4) The u-boot config target is incorrect. am335x_evm_config is the old target, the new target name is am335x_boneblack_config. 5) The kernel mentioned in the old article is not maintained. https://github.com/beagleboard/kernel.git is the old one, https://github.com/beagleboard/linux.git is the new one. The new one does not require running patch.sh or integrating the firmware. If you need to use 3.8 you can get it from the newer repo and get the latest patches as well. 6) Installing the Gentoo repository onto a 4GB SD card will result in full inodes unless partitioning the filesystem with the -T option.
These are a lot of issues indeed but I think you are talking about the black series. I was writing about the "very" old version, the "white" version (the one here http://beagleboard.org/static/images/product_beaglebone.jpg) and I tried the installation for the black for this one. It just didn't boot up but that's not that surprising because they've changed the HW in some way.
I apologize, I did not know you were referring to the white series. The old article will work, but if you have the opportunity maybe you can try using an updated u-boot and kernel with your older hardware and a few modifications (and update the Wiki so others can benefit). First, I am not positive but I believe you will want to use the am335x_evm_config target with a newer u-boot (as the older article mentions), but it will expect a ubifs filesystem not ext4. You can change this either in the kernel configuration boot options, or with a uEnv.txt file, or by creating a ubifs filesystem for the root partition, or by modifying "u-boot/include/configs/am335x_evm.h." The second issue would be in your kernel compilation: LOADADDR=0x82000000 is probably incorrect for your hardware. Newer kernels require you to specify this, but I do not know what to set it for the older hardware. You may find a hint in the u-boot source for the am335x_evm_config target, or a web search.