Well, for translations you can select Addendum under the Status menu, but that doesn't appear to be an option for hacks. I would suggest submitting your hack as a new submission and noting in the description that it's an update to someone else's hack. List yourself as the author in the submission and give credit to the original author in the description and documentation. If Nightcrawler wants to add Addendum as an option for hacks, he can edit your submission to reflect this.