Maybe when you are using nightlies for OSX from the Hudson or you compiled current git branches, you missed fgcom. I pushed a Xcode project to compile FGCom 1.2 for OSX >= 10.5.8/intel (no ppc!). There are some small changes in the source, also for the iaxclient lib, but 99,98 % is still the famous fgcom code from Holger Wirtz of course.
There is also a package in the project (FGCOM12OSX.pkg) to install a precompiled binary for OSX 10.5/10.6 i386. You will find the files here: http://gitorious.org/fgcom-for-osx/fgcomx
Testing and feedback welcome.