If I understand, you have a list of words you would like to make italic. For this, use the GREP tab in find/change.
put the list in parenthesis; put \< before the list and \> after it. put a pipe | between the words.
This finds each of the words, but only as whole words.
(I've added red to my italic style just so the result would show up better here.)
If your list is as:
+ 5,986 other words ( )
Use Multi-Find/Change and do it in a simple click!