http://34reqsy6tqou6avwrkm23s4mpkrwz3drtq2e5yr7sywi76h7plnaahad.onion/articles/linux.xhtml
In come the Slackel (http://www.slackel.gr/repo/x86_64/current/) and SlackOnly (https://packages.slackonly.com/pub/packages/14.2-x86_64/) repositories. Just start up Gslapt, go to Preferences - Sources, click Add, and copy those links. Remember, though, that you can easily break shit if you aren't careful - a repo can, for example, pull in a library that a package requires, and that one will replace the one you had before - breaking everything that was dependent on it.