To compile the help source files into something (hopefully) more usable, you should have the following programs:
A copy of the help source files and images;
Your favourite command-line XslT processor (Saxon is a very good cross-platform processor)
The DocBook XML files - the currently used version is 4.2;
The DocBook XslT files - the currently used version is 1.5.3;
The Microsoft HTML Help Compiler (hhc.exe) if you plan on producing CHM files.