[kh99]

I think you could use vB_ActivityStream_Manage. If you look at includes/class_dm_threadpost.php, for example, and search for vB_ActivityStream_Manage, you can see where posts are added to the activity stream. (Edit: maybe you've seen this already, based on your post above). But I think you need to first add rows in the activitystreamtype table and the package table, then also create classes to handle your type or types and put the files under vb/activitystream (with subdirectories, file names, and class names corresponding to the fields you added in the database).

I haven't done this myself or else I'd try to give more details, but I think if you look at the existing db entries and files under vb/activitystream, you can probably figure it out.