This tutorial is great:
http://www.macsat.com/ipkg.php
If you are using oleg, replace the line "ipkg.sh install ipkg" with "ipkg.sh install ipkg-opt"

After that you can choose a package from this list:
http://ipkg.nslu2-linux.org/feeds/op...table/Packages
For example if I wanted to install abook, the first package on the list I would type "ipkg-opt install abook" and it would download, install and configure the package.