If you ask Stihl, it can't be done. But it can! Do a search for "converted an MS250c to an ms250" and you should find a post on arboristsite.com with info. You will need a new starter assembly and flywheel. Looks like it's fairly easy to do.
Make sure the carb os adjusted right, I have a ms250 and after the first year it seems to get harder and harder to start, turns out the carb was way out of tune! I reset it back to stock and then dialed in so it started and ran like new, now it starts on about the 3rd pull every time.