spamcheck.rules file and headers

[ram]

I use in my MailScanner.conf
Spam Checks = %rules-dir%/spamcheck.rules
to define which ids get spamchecked and which dont



From:   160.83.52.      no
From:   default yes


Can I add a special spamcheck header ( added thru a milter ) 

if header X-Spamcheck: yes ,
      then do spamchecks 
else 
     no
fi




Thanks
Ram