Is there a way to modify the search screen? I was able to modify the Lucene search screen, but I am trying to modify the search screen used to find items when adding them to slots. We would like to provide more fields on which the user can search for content items.
Which search screen are you looking at? There are several different ways to search for content in a slot, and the interfaces are not exactly the same on all of them.
The search object used for the slot searches is RC_Search.
Open the workbench and open UI Elements Design.
Expand Content Explorer ->Searches -> Standard and then open the RC_Search.
Customize the fields and save the search.
Hard refresh the browser(Ctrl + F5 key).
The slot search should show the customized fields.