save-hook [!]pattern filename
This command is used to override the default filename used when saving messages. filename will be used as the default filename if the message is From: an address matching regexp or if you are the author and the message is addressed to: something matching regexp.
See Message Matching in Hooks for information on the exact format of pattern.
save-hook me@(turing\\.)?cs\\.hmc\\.edu$ +elkins save-hook aol\\.com$ +spam
Also see the fcc-save-hook command.