In my last blog-post I described how to enable meta-data for folders. Even though you can configure workflows for your custom content-type (of type “folder”), there seems to be no way to actually start those workflows. There is no context-menu entry to start such workflows as for any other content-type.
But there is a way! If you happen to know the right URL to start workflows … just call
/_layouts/Workflow.aspx?ID=[ItemID of the folder]&List=[GUID of the list]. Just insert the appropriate values and off you go.