Gem in a Box

Add this server to your Gemfile, then paste gem lines from below into the block

source "https://rubygems.vpsfree.cz/" do gem "..." end

If you needed credentials to get to this page

bundle config set --global rubygems.vpsfree.cz username:password

Without Bundler

gem install GEMNAME --source https://rubygems.vpsfree.cz/