I've also testet building lejos on OS-X.
The very first thing I did was to install the XCode-Tools of my MAC Install Disk. They include gcc, make and ant.
java and javac resist in the Folder /System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Commands
that's why there is no bin-Directory. Therefore I made a symlink to it (ln -s Commands bin).
After that I downloaded the libusb package and extracted it. I followed the instructions of the INSTALL file. That was running ./configure, make an make install.
Now I changed to the lejos_bin/build/ folder and there I executed ant.
There was no failure and the binaries (including runjava) where build in the lejos_nxj/bin dir. Now I copied lejos_nxj to /opt/local/bin and configured all the system environment stuff. I had to set the env.-variables in the ~/.profile file, because I don't know how to set environment-variables in MAC-OSX. After that I could compile, link and upload a program.