In Safari (also on iPhone and iPad) you can get it to run as a bookmarklet:
1: Create a bookmark to any page, name it Mafia Helper.
2: Edit the bookmark, delete the bookmark url, and instead paste this code:
Code:
javascript:(function(){document.body.appendChild(document.createElement('script')).src='https://dl.dropboxusercontent.com/u/15215428/mafiahelper/Realms%20Beyond%20Mafia%20Helper.user.js';})();
This modifies your bookmark so that it runs a script that loads the Mafia Helper script when you click the bookmark.
3: To use Mafia Helper, navigate to a mafia thread, then select your Mafia Helper bookmark. The Mafia Helper script will load and the Mafia Helper functionality will appear.
4: When you switch pages the page reloads and you unfortunately have to reselect the Mafia Helper bookmark to reload the script. It's a bit clunky, but you get used to it. Also, you can modify your forum profile settings to display 200 posts per page to mitigate the problem.