Download TeXcount (version 3.2.0.41): script and documentation.
The documentation, included in the download package, explains how TeXcount works, including its strengths and short-comings. It also explains the options and how you can add new macro handling rules.
The script requires Perl. This is standard under Unix/Linux. A Perl version for Windows is ActivePerl.
Overview of older versions (available for download) and change history.