Perhaps I don't understand your problem clearly...but this is one simple approach using the current tools to search for the password for the Kinook forum.
Given your custom Password Template with attributes of UserName and Password and using the ItemTitle as the service that I need the password for.
Create a new Saved Advanced Search and name it Password <<the "Search Template">>
Search Parameters:
ItemTitle equals Kinook <<allows you to type in search parameter>>
and TemplateItem equals Password <<the row that only matches password items>>
check boxes blank.
Now I can just select the Advanced Search Password in the Data Explore and change the value of Kinook to the service I want to search for.