Another Update: how to get rcxcomm working with OS X 10.2

The problem with the rcxcomm stuff under 10.2 is that the headers from the JNI under 10.2 have incorrect links and therefore don't work. To fix it, you simply need to add to the line in lejos_2_1_0/rcxcomm/src/Makefile where CCOPT is defined:

 CCOPT = -g -O ${JNILIB_TYPE} -framework IOKit -framework CoreFoundation -I/System/Library/Frameworks/JavaVM.framework/Headers -I/System/Library/Frameworks/JavaVM.framework/Versions/1.3.1/Headers

The latter part is the new one - I simply added the correct include path and then it finds jni.h. And it can compile. However, I haven't tested yet whether the whole thing actually works.