The Sony-Ericsson W880i is not supported on iSync 2.4. The workaround, as usual, includes modifying the metaclasses. This time, however, the info.plist file should also be modified.
Just duplicate the SonyEricsson-W810.phoneplugin (located in /Applications » iSync » Control-click and show package contents » Contents » Plugins » ApplePhoneConduit.syncdevice » Contents » Plugins), change the info.plist and metaclasses.plist entries in the duplicate to w880, and you must also change the com.apple.usb.vendorid-modelid to 0xD068 in order for USB to work.
Rename the duplicated folder to SonyEricsson-W880.phoneplugin. You can just create PhonePlugins within your top-level Library, or place it with the others as bove. Don't forget to make your black or silver metal TIFF icon.
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