Typical answer from an uneducated DNS expert.
Jo Rhetts comments and experience are simplistic in nature
and uselss at best.
Given that your SOA DNS is one it would be quite simple to do so.
If the Domains in question are SOA'd at many different
sources than I would say you have a bit a work in front of
you. You would have to contact each of the SOAs and change them.
If your sourcing your own SOA than its simple. Contact me off
list and we can discuss the details.
Cheers,
-Joe Blanchard