Tricky question here.
If the watch case is made of metal, you will have no problem finding a screwdriver in some electronics parts store.
But be careful!!, if your MK has got a policarbonate case you are in danger by doing it yourself.
May happen you damage the screws head , and then you have to buy a new (and really expensive) case for your beloved watch.
If this is your case, I'd rather took it to a Michael Kors watch shop to do the job. It can save you a lot of money.
Michael Kors Watches MK