Is it possible to update the value of an existing tag of a Payment XML file before the formatting of

Is it possible to replace or update the value of an existing tag of an Payment XML file before the formatting of the payment batch completes?
If yes, where may I find and read examples of how it can be done?

I know about the IBY_FD_EXTRACT_EXT_PUB package. But it appears it is only for adding or "extending" XML tags to the Payment XML file.
Please advise. Thanks.