Basically any shop, that has the catalogues, could order a shock for you. Ohlins would be the most common, that you would order through a shop. You can order a custom Penske or Hyperpro shock, directly from the manufacturer/distributor. Race-Tech is now doing shocks also, for a limited number of bikes.
caboose483 gave some good advice regarding shops, to do the work. Of the listed ones John Sherrard, at Accelerated Technologies, would be the acknowledged master IMHO. You would have to ship your stuff to him though, since they're in Lakefield, Ontario.