Well at least here in Finland, where we also have conscription, you go to a normal prison and serve six months (or at least it used to be 6months, the same as the shortest conscription time).
That hasn't been the case for ages in Finland. These days you get 6 months of "house arrest" if you refuse conscription. Electronic tagging that is. You are allowed to leave your house to go to the grocery store, to work or to study etc at predetermined and agreed upon times.