Yes, you can specify the list in the Look In field by prefixing the name with an equal sign, e.g.
Look In: =C:\LoadList.txt
FileLocator Pro will then load the text file and search each location specified in the list. Each location in the list can be either a specific file, as you require, or a folder.
You could also perform the search by concatenating the list into the Look In field, e.g.
Look In: \\Server\Folder\Info.txt;\\Server2\Folder\Archive.txt;\\Server3\OtherFolder\Backup.txt