I have successfully connect my Palm IIIxe to my Mac Mini (running Tiger), and sync'ed it with iCal and Address Book using iSync.
Summary of steps:
- Bought Keyspan USB-Serial Adapter, model #USA-19HS.
- Installed the OSX software that came with it, then connected the adapter.
- Connected my Palm serial cradle to the adapter, then put the Palm in the cradle.
- Downloaded and installed the Palm Desktop software for OS X. (Note: Must be installed as root; the installer doesn't give you the opportunity to authenticate.)
- As root, ran each of the Palm software apps that I just installed (there are four or five of them). In particular, HotSync Manager and Conduit Manager.
- Still as root, ran iSync, added the iSync conduit to the HotSync Manager.
- As root, sync'ed with the Palm. (Not sure if this step was necessary, but it didn't do any harm.)
- Back as a regular user, ran HotSync Manager, made sure the Keyspan adapter was checked, so that HotSync Manager was listening to it.
- Ran iSync, and (again) added iSync conduit to the HotSync manager.
- In iSync, enable Palm sync'ing.
- In iSync, added the Palm device.
- Clicked the "Sync" button.
The only part that isn't documented is the doing stuff as root bits -- in particular, running the HotSync Manager and iSync as root first, before doing it as a regular user. Fortunately, I found that info here on this board.

