[Exim] SMTP authentication

Sorry if this is a bit vague, but I'm an exim newbie.

I have and read most of the O'Reilly Exim book and it helps a bunch. I was
trying to get smtp authentication working, and I'm not having much luck.

I would like to start with LOGIN authentication and eventually move to a
MySQL database. I see that the book and FAQS say that both can be done, but
don't give direct examples, only generic commands.

Does anyone have a direction to point me towards? I am running exim 3.12
that was added from the Debian potato 2.2 official install CD. I have tried
LOGIN auth. using the following format:

# login:
# driver = plaintext
# public_name = LOGIN
# server_prompts = "Username:: : Password::"
# server_condition = "${if
crypteq{$2}{${extract{1}{:}{${lookup{$1}lsearch{/etc/exim/passwd}{$value}{*:*}}}}}{1}{0}}"
# server_set_id = $1

I have copied the data from /etc/passwd for a test user, and cannot get the
system to authenticate. Any help (or newbie bashing) would be greatly
appreciated.

Thanks in advance.