The audio stuff doesn't come from L-SMASH, Kovensky wrote it for GSoC. FFMS2 and libav support are also default in x264. The only patches JEEB uses are L-SMASH muxer, fade-compensate, and fgo. These patches are all rather common (L-SMASH a bit less so, but only because VFR_Maniac writes code nobody else gets) and can be easily built on OSX. Kovensky is also a mac user and a pretty nice guy, maybe try asking him for a compile?
On the site, iirc the one who reverse engineered ALAC (and everything else RE'd in libav) was kshishkov, man has a gift for it.
@Kira: sx264 uses Qt, building it on OSX takes about 3 minutes. Being able to fuck with CLI in a GUI is stupid no matter what your exp is. Better to just have regular graphical opts with more useful names. If you can use CLI, then just use it normally. Otherwise stop pretending and halfassing it.