I have created an orb that makes the installation of dependencies/libraries from npm, maven and pypi packagecloud repositories easy! I personally felt there was a lack of documentation and guidance on packagecloud-CircleCI integration, so I hope this helps.
Source and README: https://github.com/grantisdale/circleci-orbs
CircleCI orb: https://circleci.com/orbs/registry/orb/grantisdale/packagecloud
Of course, feel free to commit PRs/raise issues as you see fit