At a minimum, please install the Optware Bootstrap using Preware. The instructions on this page assume that you have done so.
"Raw" Optware packages vs. mobi.optware.* packages
As mentioned previously, the Optware feed from preware.org includes a selection of popular packages. These package files follow the pattern mobi.optware.*.
There are hundreds of Optware packages that are not available from preware.org. These packages are hosted at nslu2-linux.org, and we will refer to these as "raw" Optware packages (or "the nslu2-linux.org Optware packages"). One other important distinction is that "raw" Optware packages are managed using the ipkg-opt command, while the all packages installed by Preware (including the mobi.optware.* packages) are managed under the covers using the stock ipkg command.
Let's re-state the advice that if there is a mobi.optware.* version of the package you are looking for you should use Preware to install it instead of using the "raw" Optware package.
Installing "raw" nslu2-linux.org Optware packages
Make your filesystem read-write
mount -o rw,remount /
Then you need to download a fresh copy of the package list from nslu2-linux.org.
Then you can use the list, list_installed, info, and install commands as needed
ipkg-opt install python25
Don't forget to make your filesystem read-only once you're done.
mount -o ro,remount /