Hello,
That is a great feature, but it's not really within the realm of an "HTML Validator" so there are no plans to implement such a feature in
CSE HTML Validator.
I would suggest using a 3rd party search and replace program. One I have used before is
Replace Text:
http://www.ecobyte.com/replacetext/Unfortunately it may have issues with Windows 7.
This old topic on the subject may also be of interest:
viewtopic.php?f=6&t=97