Granite UI Workflow Inbox Customization

Anyone have any links to information or tutorials on customizing the new Granite UI workflow inbox? With the classic ExtJS inbox a custom dialog for a workflow step could be designated so information relevant to the workflow could be captured. This custom dialog path is then passed along in the inbox list json handler (/cq/workflow/components/inbox/list), which was then picked up by one of the task completion handler scripts (i.e. /cq/workflow/extensions/inbox/tbar/complete.js). With the new Granite UI inbox an item in the notification list on the notification page (/libs/cq/workflow/content/notifications) passes its info to the appropriate item and action handler (for example, selecting a workflow item from the notification list and clicking on the complete button calls the completeworkitem handler in the notifications jcr node). That handler specifies a path to an appropriate granite component (in the case of a workflow item: /libs/cq/workflow/content/notifications/completeworkitem.html). The jcr node there (/libs/cq/workflow/content/notifications/completeworkitem) contains a description of the content to render, but doesn't, as best as I can tell, offer any way to inject custom fields for user input, is there a hook that I'm missing, or perhaps override the node for specific workflows? 

Thanks,

Craig