The basic procedure is to follow the mac or linux build guides (using Fink to get the dependencies or DarwinPorts if you're stubborn). However I would like to statically-link in all the CS & CEL plugins to keep the build size down. To do this, when you build CrystalSpace, "jam libs staticplugins cs-config" instead of "jam libs plugins cs-config". This might fail if some other stuff fails to build, but it should be possible to get around this by editing mentions of the failed plugin out of ./out/macosx86/optimize/libs/crystalspace_static.jam and retrying. If there are many failures then something else is probably broken.
Do the same for CEL, and when it comes time to build planeshift, jam client_static. PM me or speak with me on IRC if you're having trouble or questions.
Thanks!
Daniel