This is how I went about adding support for my Nokia 9300 under iSync 2.3 in 10.4.7. First go to /Applications -> iSync -> (Control-click and choose Show Package Contents) -> Contents -> PlugIns -> ApplePhoneConduit.syncdevice -> Contents -> Plugins -> Nokia-9300i.phoneplugin -> Contents -> Resources.
Now make a duplicate of MetaClasses.plist so you have a backup if something goes wrong. Open MetaClasses.plist with TextEdit,co or any other standard text
editor.
I have to warn you that the way I went about this removes support for the Nokia 9300i, and adds support for 9300. Replace this code (at the end of the file):
<key>com.nokia.9300i</key>
<dict>
<key>Identification</key>
<dict>
<key>com.apple.usb.vendorid-modelid</key>
<string>0x0421/0x0453</string>
<key>com.apple.cgmi+cgmm</key>
<string>Nokia+Nokia 9300i</string>
</dict>
<key>InheritsFrom</key>
<array>
<string>family.com.nokia.9300i</string>
</array>
<key>Services</key>
<array>
<dict>
<key>ServiceName</key>
<string>com.apple.model</string>
<key>ServiceProperties</key>
<dict>
<key>ModelName</key>
<string>9300i</string>
<key>CompanyName</key>
<string>Nokia</string>
<key>ModelIcon</key>
<string>com.nokia.9300i.tiff</string>
</dict>
</dict>
</array>
</dict>
</dict>
...with this code...
<key>com.nokia.9300</key>
<dict>
<key>Identification</key>
<dict>
<key>com.apple.usb.vendorid-modelid</key>
<string>0x0421/0x0453</string>
<key>com.apple.cgmi+cgmm</key>
<string>Nokia+Nokia 9300</string>
</dict>
<key>InheritsFrom</key>
<array>
<string>family.com.nokia.9300i</string>
</array>
<key>Services</key>
<array>
<dict>
<key>ServiceName</key>
<string>com.apple.model</string>
<key>ServiceProperties</key>
<dict>
<key>ModelName</key>
<string>9300</string>
<key>CompanyName</key>
<string>Nokia</string>
<key>ModelIcon</key>
<string>com.nokia.9300i.tiff</string>
</dict>
</dict>
</array>
</dict>
</dict>
[robg adds: You shouldn't technically need to remove the other code; just add the above as a new section, as in the other Phone hints, and you should be good to go.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060701092537685