Problems installing 1.8.5 under OSX Tiger PPC

I just tried to install 1.8.5 under OSX Tiger PPC and here’s what I get

I’m following the tutorial on hivelogic which refers to 1.8.4

RDoc failure in mkconfig.rb at or around line 19 column 11

Before reporting this, could you check that the file
you’re documenting compiles cleanly–RDoc is not a
full Ruby parser, and gets confused easily if fed
invalid programs.

The internal error was:

/Users/robert/Archives/ruby-1.8.5/lib/rdoc/parsers/parse_rb.rb:
1938:in parse_method': undefined methodname’ for
#RubyToken::TkLPAREN:0x184e7de4 (NoMethodError)
from /Users/robert/Archives/ruby-1.8.5/lib/rdoc/parsers/
parse_rb.rb:1637:in parse_statements' from /Users/robert/Archives/ruby-1.8.5/lib/rdoc/parsers/ parse_rb.rb:1570:inparse_toplevel_statements’
from /Users/robert/Archives/ruby-1.8.5/lib/rdoc/parsers/
parse_rb.rb:1406:in `scan’
make: *** [do-install-doc] Error 1