I've never tried with a differential backup, but it makes sense that it should work: See the following from http://msdn.microsoft.com/en-us/library/ms187495.aspx:

1.Back up the active transaction log (known as the tail of the log). This creates a tail-log backup. If the active transaction log is unavailable, all transactions in that part of the log are lost.

2.Restore the most recent full database backup without recovering the database (RESTORE DATABASE database_name FROM backup_device WITH NORECOVERY).

3.If differential backups exist, restore the most recent one without recovering the database (RESTORE DATABASE database_name FROM differential_backup_device WITH NORECOVERY).

Restoring the most recent differential backup reduces the number of log backups that must be restored.

4.Starting with the first transaction log backup that was created after the backup you just restored, restore the logs in sequence with NORECOVERY.

5.Recover the database (RESTORE DATABASE database_name WITH RECOVERY). Alternatively, this step can be combined with restoring the last log backup.

Apart from step 5, this is where you want to be at when setting up the partner...