I'm not sure. I suppose that any program could do it if they wanted to, but I don't know that they would really bother.
Here is what I don't understand about IM/Neuro. What does an IM/Neuro person do that a straight Neuro person cannot? I mean, what does that extra two years of IM buy you? From an outpatient clinic perspective, there is a looming shortage of neurologists, so it isn't like you won't be able to find enough neuro patients to fill your day. In the hospital, you will still just be general IM, so you won't even call that many less consults than your neuro colleagues. Plus, neurologists already have a full year of IM, and they pick up more relevant IM as they go.
So, I'm not discouraging this course of action, I would just like someone to help me by explaining the motivation.