[Exim] Exim + LDAP + FreeBSD Howto ?

Hi,

I've had a read through the documentation and haven't
found it very useful in trying to set up a mail server
which doesn't have entires for each account in the password
file. I'd like to use LDAP for authentication only.

Can anyone point me in the direction of some good
documentation or give me some pointers?

I'm completely new to Exim and LDAP (i'm told it would
have been a headache with sendmail).

Thanks,
Adrian.