As a follow up to the Palm IRSync hint, I have information on how to get your Handspring Visor or Visor Deluxe to IR sync in OS X.
First, go to Palm's IR Enhancement download site and download the IR Enhancement package in zip format (to make it easier to open). Expand it on the desktop (or wherever) and install Serialirpnl.prc and Serircommlib.prc to your Visor via the USB Cradle.
Next, download the beam sync enabler package. It includes a more descriptive text file that explains everything in it. Expand the package and install bsync-e.prc onto your Visor.
Restart the Visor when prompted and go into your Preferences panel. Turn on Beam Sync-ing and follow the rest of the original tip on doing IRSyncs with Palm Desktop 4.0!
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020408005800466