I could not find any directions for this specific model but after broadening the query a bit I found this.
Fortunately Nokia 6288 is almost identical to 6280, which is supported by iSync .
As the article says... First open /Applications: iSync.app: (Control-click and choose Show Package Contents): Contents: PlugIns: ApplePhoneConduit.syncdevice: Contents: PlugIns: PhoneModelsSync.phoneplugin: Contents: Resources: MetaClasses.plist file in TextEdit, and add the following XML lines:
<key>com.nokia.6288</key>
<dict>
<key>Identification</key>
<dict>
<key>com.apple.cgmi+cgmm</key>
<string>Nokia+Nokia 6288</string>
<key>com.apple.gmi+gmm</key>
<string>Nokia+Nokia 6288</string>
<key>com.apple.usb.vendorid-modelid</key>
<string>0x0421/0x045A</string>
</dict>
<key>InheritsFrom</key>
<array>
<string>family.com.nokia.series40.3rdEd.bus.usb-bt</string>
</array>
<key>Services</key>
<array>
<dict>
<key>ServiceName</key>
<string>com.apple.model</string>
<key>ServiceProperties</key>
<dict>
<key>ModelIcon</key>
<string>NOK6280.tiff</string>
<key>ModelName</key>
<string>6288</string>
</dict>
</dict>
<dict>
<key>ServiceName</key>
<string>com.apple.synchro</string>
<key>ServiceProperties</key>
<dict>
<key>MaxCityLength</key>
<integer>50</integer>
<key>MaxEMailLength</key>
<integer>60</integer>
<key>MaxEventLocationLength</key>
<integer>150</integer>
<key>MaxPhoneNumberLength</key>
<integer>48</integer>
<key>MaxPostalCodeLength</key>
<integer>50</integer>
<key>MaxStateLength</key>
<integer>50</integer>
<key>MaxStreetLength</key>
<integer>50</integer>
<key>MaxURLLength</key>
<integer>60</integer>
</dict>
</dict>
</array>
</dict>
After that just pair the device via bluetooth and run isync. Business as usual