The installation procedure is different for different platforms. For Windows there is a standard executable installer that will guide you through the very simple installation process. On Linux and other Unix systems there the source code distribution has to be used. The program uses the standard distutils package for deployment and the detail are in the INSTALL file in the main bkchem directory.
Also on all platforms it is possible to run BKChem directly from the source directory obtained after unpacking of the source code distribution. All the details and prerequisites are again in the INSTALL file.
The distribution of BKChem contains some basic documentation in the subdirectory called doc. It is far from perfect, but its the only one we have :)