How to use the do-it-yourself kit:

• Download the kit.
• Download and install Doxygen. There is a package for this on most Linux distros.
• Follow the shell commands below. Don't forget to use cp -i the second time, so ruby.h and intern.h are not overwritten.
  $ bzip2 -cd bundle.tar.bz2 | tar -xvf -
$ cp /path/to/ruby-1.8.1/*.c bundle
$ cp -i /path/to/ruby-1.8.1/*.h bundle
$ cd bundle
$ doxygen
  
• You should end up with a bunch of html files in documentation/html - this is the documentation generated by Doxygen. Enjoy!