If you haven’t already done so, you need to install the Developer Tools (an optional install, on your System Installation DVD). Under MacOSX 10.4, the easiest way to obtain the remaining prerequisites is using Fink. (Be sure you have unstable/main in your list of Fink trees. )
% fink install ruby ruby18-dev rubygems-rb18 rake-rb18 sqlite3-rb18 swig bison flexAn alternative (that will get you everything but SWIG is the rubyosx installer).
Once you’ve installed these prerequisites, you can proceed to the next step of the installation.
N.B.: On some Tiger systems, Ruby, as installed by either of these methods, is prone to Segmentation Faults. If that happens to you, you’ll need to back up to this point and follow the instructions in this blog post.
Back to the installation instructions.