[A CO in CO]

I'm preparing a manuscript for submission to a publisher, but one publisher
wants italicized words to be underlined and another requests that they be
italicized, no underlining at all.

Is there any way to replace the formatting code for italics with that for
underlines (perhaps similar to the "find and replace" feature) or am I going
to have to go through this monster and manually replace everything?

Thanks in advance.