Formatting of SA score in Subject?

[Jeff Morris]

I asked this question a few months ago, but still haven't found a 
solution, so thought I'd try again.

I currently have the following line in my amavisd.conf:

      $sa_spam_subject_tag = '[SPAM: _SCORE_] ';

This causes Amavis to cause Spamassassin to rewrite my spammy Subject 
headers like this:

      Subject: [SPAM: 8.353] Some Spammy Subject Here

I'd like to tweak the score format here so it has a leading zero. i.e. 
I'd like to change the formatting from "%.3f" to "%06.3f", so my spammy 
Subject headers will instead look like this:

      Subject: [SPAM: 08.353] Some Spammy Subject Here

When I asked before, it was suggested that I change "_SCORE_" to 
"_SCORE(0)_", however that did not work, it caused the literal string 
"_SCORE(0)_" to be inserted into my subject lines, rather than the 
formatted score being substituted.

Is there any way to do this?