I think it should be able to be done by moving around the folders and files, but I think there might be coding to do with the destination of other folders, since a lot of the coding depends on the other files. I want to convert the VSM mod to 1.6.2, so I can do mutant skeleton vs zombie pigmen easily.
I would rather fight the wither, because it is very challenging and really fun. The ender dragon is really easy once you have destroyed the ender crystals, and boring when he just flies away and doesn't come back for 5 minutes. If you don't have a bow, the ender dragon just takes ages to come and kill you, when the wither just gets it over and done with. I prefer the wither much more to the ender dragon. I don't know why everybody else prefers the ender dragon.