metaclasses.plist modification is required for N70 or N90 to work with Tiger 10.4.5's iSync 2.1.1 (89.0)
Navigate to Applications -> iSync -> (Control-click and Show Package Contents) -> Contents -> Plugins -> ApplePhoneConduit.syncdevice -> Contents -> Plugins -> PhoneModelsSync.phoneplugin -> Contents -> Resources
Remove any pairing first then replace the metaclasse.plist with this (N70 and N90 tiff icons included):
http://s18.yousendit.com/d.aspx?id=0SY1TC1135HR12YXWK5SNHX9MB
Do a Repair Permision after and your all set. Back up your original metaclasses.plist just to be safe.
Worked well with my N70 and N90.
PB15'/G4/SD/80GB/1GB/30GBiPodVid/ Mac OS X (10.4.5)