Little help please

http://mediaweb.aib.ac.uk/fdashow08/collins/projects/one/web/index.html

please can anyone give me the exact code on how to do this? the kirupa image pan tutorial is slightly different to the link above. With this you scroll left and right from directly in the middle, where as on kirupa tutorial, the further left or right you are across the image determinds where the left and right panning area is. I want it to always be pannable only from the middle

any help would be great thankyou