The result can be found here. I've set the default to -q 4 (quality can be from 10 which is really good to 0 which is bad). -q 4 gives me files with an average encoding rate of 116kb/s. Type oggenc -h to find out other settings although you probably won't need to set anything else. I simplified the script a bit so it's not as configurable as the iTunes-LAME one. It does work, however, and I thought someone else might find it useful.
Note: You will also require the commandline LAME encoder for this to work as oggenc doesn't list genres (which the script needs). Instructions for installing LAME can be found in this hint.
And to make your .ogg files look like other iTunes files, I've created an iTunes .ogg icon. Uncompress and place in /Applications -> iTunes.app -> Contents -> Resources/ (unless you've moved iTunes). Then open /Applications -> iTunes.app -> Contents -> Info.plist in an editor. Paste the following somewhere in the CFBundleDocumentTypes array:
<dict>Save the file and quit the editor and you should be good to go!
<key>CFBundleTypeExtensions</key>
<array>
<string>ogg</string>
</array>
<key>CFBundleTypeIconFile</key>
<string>iTunes-ogg.icns</string>
<key>CFBundleTypeName</key>
<string>Ogg Vorbis Audio File</string>
<key>CFBundleTypeOSTypes</key>
<array>
<string>PLAY</string>
</array>
<key>CFBundleTypeRole</key>
<string>Viewer</string>
</dict>

