Using Java POI in ruby?

Does anyone have any idea how to use the Ruby bindings for the Java POI
project in ruby? The main page for the project is here:
http://jakarta.apache.org/poi/poi-ruby.html. There seems to be some sort
of precompiled binary file available, but attempts to load it into ruby
lead to:

irb(main):002:0> require ‘poi4r.so’
LoadError: libgcj.so.5: cannot open shared object file: No such file or
directory - ./poi4r.so

What exactly do I need to do to get this to work? Do I need to get some
other files as well? Any help with this would be greatly appreciated.

-Thanks