G:\gems>gem install libv8-3.11.8.17.gem -l
Temporarily enhancing PATH to include DevKit...
Building native extensions.  This could take a while...
ERROR:  Error installing libv8-3.11.8.17.gem:
        ERROR: Failed to build gem native extension.

C:/RailsInstaller/Ruby1.9.3/bin/ruby.exe extconf.rb
creating Makefile
系统找不到指定的路径。
系统找不到指定的路径。
系统找不到指定的路径。
C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/libv8-3.11.8.17/ext/libv8/builde
r.rb:49:in `setup_python!': libv8 requires python 2 to be installed in order to build
, but it is currently not available (RuntimeError)
        from C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/libv8-3.11.8.17/ext
/libv8/builder.rb:35:in `block in build_libv8!'
        from C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/libv8-3.11.8.17/ext
/libv8/builder.rb:34:in `chdir'
        from C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/libv8-3.11.8.17/ext
/libv8/builder.rb:34:in `build_libv8!'
        from C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/libv8-3.11.8.17/ext
/libv8/location.rb:24:in `install!'
        from extconf.rb:7:in `<main>'

Gem files will remain installed in C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/ge
ms/libv8-3.11.8.17 for inspection.
Results logged to C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/libv8-3.11.8.1
7/ext/libv8/gem_make.out

解决方案：

G:\gems>gem install libv8-3.11.8.17.gem -- --with-system-v8
Temporarily enhancing PATH to include DevKit...
Building native extensions.  This could take a while...
Successfully installed libv8-3.11.8.17
1 gem installed
Installing ri documentation for libv8-3.11.8.17...
Installing RDoc documentation for libv8-3.11.8.17...