edit -m messages logged

I want to rewrite a few messages logged at the time cvs ci.

This is a single user home machine with just config files and homeboy
scripts under cvs.

I see a section in the manual under 
Administrative options

That shows this:
`-mREV:MSG'

Can anyone show the practical usage syntax.

I've tried various things with just cvs, and cvs admin and cvsadmin but
not getting it right.

Assume cd to checked out module

  How to change the log message in 

    ./somefile