Hi Axel,
Actually you might better enjoy
https://github.com/capistrano/sshkit - for explicitly managing stuff that isn't "deploy a web app from a git repo", we separated out the "ssh remote driver" if you could name it that way into it's own package and you'll find a tonne of examples there.
Further, you can if you need just the "bones" of a deployment, without too much of the "checkout from git, copy this, symlink that", etc just import the "flow"
http://capistranorb.com/documentation/getting-started/flow/ and you get all the hooks, but with none of the default tasks hung from them.
In the case of your "rollback" to an older package, I'd rather avoid calling that a "rollback" as that has a really specific meaning to Capistrano, which is to symlink the current-1 release timestamp directory to current.