Mac OS X isn't just a sealed bucket of bits you receive on shiny optical discs -- under the hood is software just like you and I write (just lots more of it). It's beholden to the same laws of software-physics as you and I must obey. Together we'll spelunk the moist caverns of Mac OS X using tools like otool, otx and class-dump to explore the mach-o file format. Then we'll cover current injection technologies like Input Managers (incompatible with 64-bit), AppleScript Additions, mach_inject DYLD_INSERT_LIBRARIES. Finally, we'll talk about extension technologies like mach_override and JRSwizzle.