Note: a better OS X program for managing your DMS is available here.
This site contains software better suited for the more technical, Unix expert who wants to tinker.

Managing PhatBox from OS X

Step 0: Installing the PhatBox/Music Keg

Before you try any of this, make sure your system works out of the box before trying to add any playlists. There will at least be a welcome file on the cartridge.

Besides using these OS X/iTunes native scripts, it is also possible to run the supplied Windows software within VirtualPC. This allows supported firmware upgrades and use of the far superior AT&T voice prompts. Information on using VPC is here.

Step 1: Installing cradle drivers

How to determine which cradle you have

The first time you insert the cartridge, the Disk wizard may come up, asking you to initialize the disk. If it does, Cancel this. I repeat - DO NOT initialize the drives!!! When you remove and re-insert the cartridge, PHTSYS will show up, and it will ask to initialize the disk again, cancel, eject, and PHTDTA will show up after it is re-inserted.

Step 2: Copying an iTunes playlist to the DMS

Download and install this package from the site. You have to agree to the license to the plsign utility. The rest is open source, and freely distributable.
iTunes2DMS-0.7.pkg.tar.gz It appears PhatNoise has disabled this download. Contact them directly for more information.
New for 0.7: Nicer Mac installer package. Added update database button. Installs in /usr/local. If you already have id3lib in /usr/local, it may over-write it.
New for 0.6: Fixes to modification update, all-caps M3U filenames, and more integrity checks.

After that is done, you will have a new menu item in iTunes under the script items. See a screenshot. When you select that, you will first be prompted with a dialog asking which playlist number you want the currently selected playlist to become on the DMS. The copy will happen in the background, and a dialog will pop up when it is done and safe to eject your DMS. (right-click eject, or drag it to the trash!) Do NOT pull out the DMS without ejecting it first!!!

Alternately, you can run the application separately from iTunes. It will grab a list of playlists in iTunes and the DMS, and run the copy. This is the beginnings of a much nicer UI than the script added to the iTunes menu, and currently has a progress bar!

Step 3: Submitting bug fixes and enhancements

I could really use some help getting this going. Specifically, if you know how to do any of the following, please let me know!

Source code for binary programs:
iTunes2DMS AppleScript Studio project (v0.2)