Adding index to existing table that isn't mine.

What’s the best way to add an index to an existing table that’s a third-party table?

It’s a table with an auto-increment field as it’s primary key (along with CompanyID). But when I look at the underlying views, the code is querying the table using non-indexed fields. I don’t have time, at the moment, to reach out to the third-party to suggest that they add a key to make the lookups faster mostly because I won’t have time to integrate any patch from them into my code base at this point even if they agree.

So I was thinking of adding a non-unique key on the fields that I see the view using.

Should I just add a SQL script to my customization project to add the index if it isn’t already in place?

Or is there a more official way that I should do this?