Best way to do that is fire a CB event after loading CB API then act on it in CB Auto Actions. The API will change in next CB Activity release and it will break anyone trying to use it before it has matured, but I maintain CB Auto Actions so its usage will also be updated preventing a lot of headache for anyone integrating CB Activity. See the below on how to do this.
www.joomlapolis.com/forum/153-professional-member-support/234944-virtuemart-using-new-trigger-with-cb-auto-actions#286669
The user has provided a full example for loading in CB API, loading in CB plugins, then firing a custom trigger. You would need to do the same in whatever you're wanting this in.
Also worth noting next CB Activity will have a content plugin like CB Gallery for rendering activity and comment streams anywhere content prepare is supported.