Adding a custom property to the Advanced Search Box filters

To make a custom column appear as one of the property restrictions in the SharePoint 2007 Advanced result page, you need to:

  1. Map the crawled property to a managed property.

  2. Edit the XML of the Advanced Search Box webpart to show the managed property.

An nice post detailing the exact steps is on Jonathon’s Blog: Searching Custom Column Values in MOSS 2007