[exim] forwarding to multiple addresses using ldap

Hello folks!

I am using exim4 and I have my user database on a ldap server and I use
a nice ldap user admin interface (gosa) for managing this db. Users
have an entry with dn: "cn=Name,dc=domain,dc=tld" and an attribute "uid"
which corresponds to $local_part. For some users there is an attribute
called "gosaMailForwardingAdress" which can contain one or more mail
addresses or this attribute doesn't exist at all. (Maybe an empty value
is possible, i don't know exactly?)

Now I would like to forward all messages of the given $local_part to all
specified addresses in addition to the local delivery.

I was studying the doc and faqs and was trying to derive sth from the
default config of my debian box... but actually it's too complicated to
me, because I don't know how to handle multiple address rewriting...
Maybe I should use the ldapm lookup type... but can someone give me the
golden hint?

Thanks in advance!
Wollie