Qt-wise, the packages are self-contained, that is, they already include the Qt 4.8 framework they were linked against. You only need to additionally install the SDL framework (1.2.15+), which is required for MAME & MESS anyway on that platform. The binaries require Mac OS X 10.5 or higher.
If you want or need to build QMC2 from source, please follow this FAQ!
Builds of development versions:
David Ely maintains the Mac OS X builds; he also keeps official releases and builds of recent SVN revisions on his server.
Users of older versions of this package (prior to 0.35) must first remove the old package, which was called just qmc2 and contained both variants. To do this, run sudo apt-get remove qmc2 before installing the new package(s).