Hi,
I'm sorry but i haven't found a solution jet. To be honest, i haven't tried too much though. My goal was to start investigating the connection possibilities (both SOAP and connection libs) and getting to the point of retrieving data specifying the password was enough.
About this problem: I don't know your case, but i was mainly interested in the "trusted host" possibility, since i don't have a logged-in user when the external application is running, and for that i haven't found much documentation.
If you do have a logged user and the machine is registered inside the ldap domain, getting his/her java.security.Principal and passing it to the IeConnectionSpec.setAuthUser method might work (I haven't tried so i might be wrong).
sorry that i'm not of much help. If you make any breakthrough let me know.
good luck, Marco.