extending page metadata?

Hi.

I'd like to store a short description of a page edit in the RCS file 
for the page (e.g. "added paragraph on bighorn sheep" or "spelling 
corrections").

What is the simplest and/or cleanest way to do this?

I already have a replacement for Kwiki::Edit which adds a "describe 
your changes" field to the page edit web form.  But I don't see a way 
to store this info in the RCS file without  a lot more work. 
Kwiki::Archive::Rcs stores info from the page metadata, but I don't 
see a way to hook into the page metadata storage.  (The metadata 
fields are hard-coded in Kwiki::PageMeta.)  Is there a way to 
subclass Kwiki::PageMeta without also messing with Kwiki::Pages? 
(They are contained in the same file.)  Alternatively, I could 
subclass Kwiki::Archive::Rcs, but that won't work because it doesn't 
communicate directly with the edit class.

Suggestions?

Kevin