Comment 5 for bug 831604

Ok, I managed to get this working by setting it up on a machine at home first. I login to that home machine with a local account.

Then I sync the .Private folder through UbuntuOne to my work machine.

The final bit is to use the same mount-phrase across the two machines but with different logins.
To achieve this I needed to unwrap the mount-passphrase at home, copy it to work and rewrap it there with my work login passphrase (which is using likewise to authenticate against Active Directory).

Works fine now.

The commands you are looking for are

Home machine - find out the mountphrase by unwrapping
ecryptfs-unwrap-passphrase ~/.ecryptfs/wrapped-passphrase

Wrap that mountphrase with your AD password on the work PC
ecryptfs-wrap-passphrase ~/.ecryptfs/wrapped-passphrase

Good luck