I saw compiler flags for OSX in the source tarball [1] but to install on OSX probably requires installing from source, and if my experience with using macports to install Conkeror and uzbl is any indication, installing all of the dependencies correctly is likely to be something that requires hours of tedious effort unless one is an expert. The reason for that is that luakit (and Conkeror and probably uzbl) rely on a very large stack of "non-Mac-like" software including the GTK toolkit and the X windowing system.
If you can get around in Linux, I would test drive the software on Linux to make sure it is as useful to you as you imagine it to be before doing the work of figuring out how to install it on OSX.
I will add that the difficulty of installing relatively unpopular Linux packages on OSX is one of the biggest disadvantages of OSX for me. (The unavailability of laptops in which everything Just Works is of the biggest disadvantages of Linux for me.).
I've tentatively given up on relying on software that requires X while I am using OSX: I plan to keep on test-driving such software (on Linux), and if I decide I have got to have access to it, I will switch back to Linux.
