I wanted to be able to muck around with Ruby versions and different gems without impacting the system installed ruby environment. This is how to do it
cd wget ftp://ftp.ruby-lang.org/pub/ruby/1.8/ruby-1.8.6-p111.tar.gz http://rubyforge.org/frs/download.php/29548/rubygems-1.0.1.tgz tar -zxf ruby-1.8.6-p111.tar.gz cd ruby-1.8.6-p111 ./configure --prefix=/home/norr/ruby18 make make install export PATH=/home/norr/ruby18/bin:$PATH export RUBYLIB=/home/norr/ruby18/lib tar -zxf rubygems-1.0.1.tgz cd rubygems-1.0.1 ruby setup.rb
To make all this seamless and effortless you could setup a quick script to switch the environment variables around :)