Smartlist from address

Hi, I'm new to this list. Hi everyone! :-) I hope its okay to talk
Smartlist stuff here.

I have set up a smartlist mailing list which restricts who can post
to it via an accept file. That works fine, only I'd like the messages
to appear as if they came from a single user.

I assume I need to fake the From or Reply addresses. Is there an
easy hack to the rc.custom file or a script to accomplish this?

Thanks,
davidt(_at_)mcs(_dot_)net(_dot_)au