Currently, adding a custom search column can require editing Search.pm, buglist.cgi, colchange.cgi, and list/list.html.tmpl. This process could be centralized by creating a Hook for buglist.cgi's DefineColumn function, and extending this function to control column visibility and ordering in colchange.cgi.
How is this bug different from bug 437003? It already added a hook to buglist.cgi. Is it a dupe?
It looks like a dupe. I think we didn't have it in our branch yet when I filed this.