title: Install a specific gem version with configuration options
body: <p>I'm trying to install an old version of nokogiri, but I am having trouble specifying the format:</p>
  
  <p>I'm using  </p>
  
  <pre><code>gem install nokogiri -v 1.5.2 -- --with-iconv-lib=/usr/local/Cellar/libiconv/1.13.1/lib
  </code></pre>
  
  <p>but this is not the correct syntax. Do you know how to do this?</p>
  
  <p><strong>ERROR</strong></p>
  
  <pre><code>Building native extensions.  This could take a while...
  ERROR:  Error installing nokogiri:
      ERROR: Failed to build gem native extension.
  
          /Users/boris/.rvm/rubies/ruby-1.9.2-p320/bin/ruby extconf.rb --with-iconv-lib=/usr/local/Cellar/libiconv/1.13.1/lib
  checking for libxml/parser.h... yes
  checking for libxslt/xslt.h... yes
  checking for libexslt/exslt.h... yes
  checking for iconv_open() in iconv.h... no
  checking for iconv_open() in -liconv... no
  -----
  libiconv is missing.  please visit http://nokogiri.org/tutorials/installing_nokogiri.html for help with installing dependencies.
  -----
  *** extconf.rb failed ***
  Could not create Makefile due to some reason, probably lack of
  necessary libraries and/or headers.  Check the mkmf.log file for more
  details.  You may need configuration options.
  
  Provided configuration options:
  </code></pre>