For the duration of the time there, I had a curator/evangelist whose job, along with others on my team, was to evangelize the library and to solicit input — both at the editing level, the feedback level and the submission of new patterns level.
We didn’t create from scratch in a vacuum, we had lots of conversations with teams about their work, their research findings etc. for what should be in the library to use across the network. We also did our own primary research for a variety of things — social patterns, links, call to action buttons and other elements that we could put into multiple contexts. This was research that only a central team could do as the business units didn’t always care if a solution worked elsewhere or not.
With my clients, I have been brought in to help the curator get a program going and often we start with a workshop — to identify interactions for becoming pattern candidates and to write the patterns—and all relevant and interested designers and developers are invited to the workshop. That way everyone is bought in, are co-creators and are much more likely to champion the continued creation and adoption.
But it takes both the push and pull.