There are two ways to install the Crossfire clients, one is Fink which is a project that ports Unix software to Mac OS X. The other option is to compile Crossfire via source code.
Ok there are a few ways to get the crossfire client to work on OSX.
Quick Instructions:
Note: Leopard Users will need to compile from source as there is binary release available
There is a version of the the cfclient on fink but it is version 1.7 which does not have the bells and whistles that are included in 1.10 besides why run 1.7 when you can just run 1.10.
Once the client has been successfully installed, there is a .dmg file available for download that will let you run any of the three clients (crossfire-client-x11, crossfire-client-gtk and crossfire-client-gtk2)
Installation instructions:
Note: With the GTKv2 client, after first launching click on the green “+” which will then let you resize the client window.
Note: The binary files where compiled on Os X 10.5, I don't know as of now if they will work on past versions.
Compiling from source code requires some additional files to be downloaded.