How to record the score?

I love the scoring mechanism of procmail. I use it as a semantic filter 
against spams, as a way to filter out messages in foreign languages like 
english, etc.

To tune it, I would like to know the score that was obtained by a 
message. I would like to have something like that:

        :0f
        | formail -A "X-score: $SCORE"

But I cannot find such a variable ($=, which is documented in 
procmailsc's page can be used only in conditions, not in actions).