On my desktop computer (where the music files reside), I exported my library in XML format. Then in TextEdit I replaced all instances of the local path to the music files with http://xx.xx.xx.xx:8888 (i.e. MP3 Sushi's path to the music files). Then on my laptop at work, I imported the XML file. VoilĂ ! I can shuffle, make playlists, and search my entire music library through iTunes over the Internet.
One pro of this solution is that is should also work with the Windows version of iTunes, although I can't confirm this. One con of this solution is that you can't fast-forward or rewind through a given song. Users with a dynamic IP address should probably use a dynamic DNS service (such as dyndns.org to make sure the imported library always points to the home library.

