To Oversight,
I do not think it is possible to have "Thoracic kyphosis", and not have protracted neck at all. Maybe yours isn't significant, but there is usually some level of it. Look up "Deep Neck Flexor exercise" while you are at it, and also "cervical spine retraction extension exercise". Don't do too much of them.
The Thoracic spinal stretch exercise, you should have your arms relax and out to the side at 90degress, allow head to relax and drop down onto bed, don't use pillow unless you have more than mild pain in the neck/dizziness. Use the head and arms' weight to stretch the spine. Perform with the roller at T1, T2 and T3 (top 3 levels of thoracic spine), hold for 2 minutes each.
Neurospast stated a good point. Make sure after training your muscles, especially shoulders and back muscles, you also train them to fully relax. It actually takes effort in the beginning, because its not easy to notice those low level tension in the muscles when they are there most of the time. I have personal experience with this, and found the process of self hypnosis, really helps.
Have fun!