Is there a "set" way of making it a generator?

Seemingly seems to finish returning a page set...? And using that for storing things?

Yes, you need to fill a PageSet object with the revisions generated by usercontribs. However, there are no existing generators that generate revisions rather than pages because ApiPageSet::processDbRow() only supports titles at this point. However, ApiPageSet does support loading from revids through populateFromRevisionIDs(), so adding an equivalent of processDbRow() for revisions or detecting the difference between the two in processDbRow() shouldn't be too difficult.

In T21314#231121, @Catrope wrote:

However, there are no existing generators that generate revisions rather than pages

There is deletedrevisions/alldeletedrevisions now, so I suppose this is now easier?

usercontribs does not expose flagged state (for the FlagRev extension), so using it as a generator would be required for custom patrolling interfaces on wikis with FlagRev.