SASL and mail attribute help

["Al Pacifico" <pacifico@drizzle.com>]

I wish to authenticate using SASL DIGEST-MD5 against the mail and
userPassword attributes. 

The examples at OpenLDAP show use of the uid attribute, which is not present
for all entries in my directory. I'm not sure how to map to the correct
authentication request DN.

Could someone post the pertinent section of slapd.conf to accomplish this?

I believe this is the correct forum for this request; if not, please direct
me to the correct one.
Thanks.
-al