Here comes tutorial:
1. Prepare separatly each image in 16 bits
mode. Remove noise, sharp it, work curves, check distortions ect. Save all. It is important sicne next step doesnt work with 16 bit images, so lets squize all juices here.
2. Photoshop -> Automate -> Photomerge
Play with perspective and cylindrical settings for the best match. Dont forget check on 'keep as separate layers'
3. Once is done you will have nice set of layers. Some of them will need fine adjustment such as moving, transform etc to get the best result.
4. Then apply masks and make a magic. Brush size and softnes depends on detail.
5. Dont forget to clean up your swap file partition before since you will need a lot of memory
Regards,
K.Polak
PS Forgot to mention, this was shot from hand