That sled looks like it has attachment slots for a tow bar, I assume for towing behind a snowmobile. There is a Koenders sled (that is the brand I have) that comes with something similar, and has the tow bar available. So, it should be fairly easy to get someone to make a set of shafts that have ends that will attach to those attachment slots. You would have to look at the particular sled you want to use to see how exactly the shaft would have to attach on to it.
The biggest Koenders sled that I have does not have a tow bar option. However, I have considered how I could add shafts--I figured that I would just drill a bigger hole in the plastic rim (there is a small hole already, for a rope handle)--then could get shafts made with a fork (sort of) end--shaft end would fit over the sled rim, top & bottom, slide a bolt through the whole thing, and that would do it. Once the shafts are attached to the sled the singletree is easy--it can just be attached to a crossbar on the shafts.