Twine superhero Leon Arnott has created a bookmarklet that allows authors or curators to quickly add new Twine-based entries to the IFDB. Once this JavaScript one-liner lives in your browser’s bookmarks, you can navigate to an online Twine game, open the bookmarklet, and follow the prompts.
(An improvement, should anyone feel up to it, would involve letting one back out of the process via the resulting dialog’s Cancel button. Feel free to tell me about the existence of improved versions. I share this code as-is because helping the Twine community sit at the larger IF table makes me happy, and also because lazy.)