OK - I finally managed to get DarwinPorts installed on AirTrain (the iMac). I couldn't get it installed under OS X 10.2 - it complained that TCL was built without threading enabled.
Now that I have OS X 10.4 and the Xcode tools, DarwinPorts installed without a hitch from source.
I am now able to successfully build all the other required libraries that I need to get 7DS running on the Mac, including:
(and maybe some more? I forget.)