Adding properties to the Advanced search webpart in SharePoint 2007

Jonathon's Blog: Searching Custom Column Values in MOSS 2007Very detailed steps on creating custom properties in the advanced search. Lots of people here asking whether it would be possible to have a dropdown list with the choices available, such that the search options of the users are limited.This is something I am highly interested in, so I'd be interested if someone posts a solution to this.