How do I teach Spam Assassin?

[Christofer C. Bell]

I've been collecting spam email that's gotten past my Fedora Core 1 
installation of spam assassin (spamassassin-2.63-0.2) and I'd like to "teach" 
spam assassin about these messages (update the heuristics to be able to 
filter these messages that are getting past the filter by default).

Someone posted a command that does this on the list some time ago and I've 
unfortunately lost that message.  How can I teach spam assassin (system wide) 
about this email?  Thanks!

--
Chris

"Build a man a fire and he will be warm for the rest of the night.  Set 
a man on fire and he will be warm for the rest of his life."  -- Unknown