The Mac port is fairly easy to build, in general. I use DarwinPorts to install the necessary libraries beyond what Tiger gives you. There is a README.BUILD.txt in the macosx directory of the subversion sources that you can look at for more information.
What needs to be done with the Mac port is this:
1. Fix existing bugs (currently loading/saving games is broken, apparently due to changes in how script state is saved; and there may be other crashes that occur)
2. Create an Xcode project to build it in a more robust way. This would ideally include Xcode projects for all required libraries so that they are turned into frameworks that can be used by Warzone, to make the whole process of building them easier. Also, having Xcode projects for everything would make it much, much easier to create universal binaries.
I lack Xcode experience so I haven't begun #2 at all. #1 will probably require use of saved games from the Windows or Linux ports to help track down which things are being broken. Usually, these are endianness issues - the majority of my work in porting the game to the Mac consisted of endian-fixing code in appropriate places. In fact, I just added an endianness fix last week that makes the colors come out right (you may have noticed that many colors are not correct in 2.0.5 and earlier).
Any help you can offer is much appreciated. If only I had waited a year to get my PowerMac, I would have a Mac Pro instead.