Technically this is off-topic for blender.stackexchange but I expect several people will be interested and have trouble getting this addon working so I will add this info here.
Cube surfer is written in cython not python. The cython project is a kind of hybrid between C code and python code. You need to convert the .pyx file in CubeSurfer to a c file then compile it into a shared library. You will need to install cython and a compiler if you don't have them already.
There is a setup64.py to build it included with CubeSurfer, it is only setup for windows, for other platforms you will need to make some changes.
If you have trouble building this you will need to ask for help on irc or stack.overflow or the CubeSurfer developer
It could be possible that builders may offer this addon pre-compiled with graphicall builds - there don't appear to be any yet.