I am INTP and I could see myself being a consiglieri-type, and depending on the situation or my comfort level with the boss, probably the consiglieri himself. I say this because I've been in situations before, even recently, where I had to give advice to somebody in charge and I can come to a logical decision with relative ease, approaching the problem from directions that others wouldn't have thought to.
Part of the consiglieri's task is to represent the family from the legitimate sector as well as the illegitimate aspect of the family business. For this reason, I would probably not make a good consiglieri as my people skills aren't very well developed; I simply don't care enough to develop them. The consiglieri's job is more than just advising, like I said.. he's the official face of the family. He is often the go-between with other heads of family. Example: The Don Stracci might have business with Don Corleone, so he is going to contact Tom Hagen, Corleone's consiglieri. Tom Hagen is going to go through everything in his head, why he's being contacted, how this could work against his boss, what the Stracci family has to gain by whatever their proposal was, ect. ect., and present this to his boss in a fashion that would most benefit him. Such is the way of an INTP. INTPs make good attorneys also, which is a definately plus for a consiglieri.
I wouldn't make much of an enforcer as we don't tend to get violent or angry very easily unless our firmest beliefs are infringed upon.. simply having a boss approach me and say "Hey, go whack this fella'," isn't going to motivate me very much to go and do it. Not only that, but INTPs don't like to be leaders or followers. As for the head of a family, I would probably be more like a Michael Corleone boss than another, secluding myself to the ones I know and not trying to bring in fresh blood to replace those that we lose.. and for that reason my family would fall much like his did. I would only want to deal with people I'm comfortable with being around, and in a business like that, you need to be comfortable around a lot of strangers.