[exim] Exim, LDAP

I trying to setup Exim (4.62) to replace Postfix (2.2.10) on an OpenLDAP

(2.2x) backend for virtual hosting (ISPMan) delivering to Cyrus IMAPd
(2.3.x).
I have the recipient verification LDAP callouts working properly
(according to exim -oMa 127.0.0.1 -bs -d).
The trouble is that the LDAP schema has both a mailLocalAddress and a
mailRoutingAddress.  Currently I'm using this LDAP call to to the
verification:
GET_ADDRESS_DATA = ${lookup ldap {\
        ldap:///BASEDN??sub?(&(uid=${quote_ldap:$local_part}@${quote_ldap:$domain}))\
        }\
}

Can I make a similar call (say remove the portion after $local_part) and
assign it to local_part in a router for Cyrus delivery?

Sample user entry for LDAP schema:

# louisk_cryptomonkeys_org, users, cryptomonkeys.org, ispman, cryptomonkeys.org
dn:uid=louisk_cryptomonkeys_org,ou=users,ispmanDomain=cryptomonkeys.org,o=ispman,dc=cryptomonkeys,dc=org
objectClass: posixAccount
objectClass: ispmanDomainUser
objectClass: radiusprofile
dialupAccess: yes
radiusProfileDn: cn=default,ou=radiusprofiles,o=ispman,dc=cryptomonkeys,dc=org
givenName: Louis
sn: Kowolowski
cn: Louis Kowolowski
uid: louisk_cryptomonkeys_org
uid: louisk@???
userPassword:: mySecretPassword
uidNumber: 10012
gidNumber: 10003
homeDirectory: /data/ispman/domains/cryptomonkeys.org/users/louisk_cryptomonkeys_org
loginShell: /usr/local/bin/bash
ispmanStatus: active
ispmanCreateTimestamp: 1141097588
ispmanUserId: louisk
ispmanDomain: cryptomonkeys.org
DestinationAddress: mx1.cryptomonkeys.org
DestinationPort: 21
FTPStatus: enabled
FTPQuotaMBytes: 2048
mailLocalAddress: louisk@???
mailQuota: 1048576
mailHost: mx1.cryptomonkeys.org
mailRoutingAddress: louisk_cryptomonkeys_org@???
fileHost: mx1.cryptomonkeys.org

-- 
Louis Kowolowski        KE7BAX                  louisk@???
Cryptomonkeys:                      http://www.cryptomonkeys.com/~louisk