Adding a custom field is possible and becomes easier with the next release of the forum software. However, allowing it to be searched isn’t as easy. The search functions scare me 8O and I don’t think my coding skills are up to modifying them to allow a custom fields to be searched.
Unless something has changed since I last looked at that mod (yesterday!) it’s only supported up to v 1.1.2 of the forum software. I’m running v1.1.3 and testing v2.01beta.
In any case I try to avoid using too many mods. Too many mods are written by people who then lose interest. As mods tend to be fairly specific to versions of the forum software, if the original author has lost interest the only choice when a new version of the forum comes along is to either debug the mod for yourself or remove the functionality. I suspect you’d all get upset if every few months I removed some functions that I’d given you a few months before. Open source software is great for generating useful small utilities that end up losing support after a short time #-o