Hi,
I'm facing the same problem, and I found two ways to solve it.
1) Populate a field in your Active Directory person documents with the Notes Distinguished name of your people, and configure your LDAP document in Directory Assistance to get this field by enabling name mapping.
2) You must install your Traveler server in a domain different from that where your users are registered. In this way you can configure an LDAP document in your Directory Assistance for your Active Directory and set "Yes" to "Trusted for Credentials" parameters, and create another document in your directory assistance for lotus notes lookup on the domain where your users are registered and set to "No" the "Trusted for Credentials" parameter.
Best Regards
Matteo