Dealing with personal space at work . . .

Like most people I’ve had my personal space invaded on a number of occasions. On public transport or the dance floor where everyone’s packed in like sardines, you tend to just deal with the fact that there are strangers standing a lot closer than you would normally allow them. When the crowds are absent however, someone who gets inside ‘your bubble’ (as my sister’s call it) can cause a great deal of discomfort.
For me, invasion of the bubble has happened a few times in the past but never with serious consequences, and not always explicitly. Every time there has been a justification for not making a scene; sometimes it is fear of offending, others uncertainty as to weather the person realises they are making you uncomfortable, or the difficulty of proving that they are deliberately trying to upset you. Regardless of the circumstances, I have yet to find a means of dealing with these people that I’m satisfied with.
Unfortunately, this invasion of personal space has lately become a problem at work. One of my superiors has a habit of standing so close that he will repeatedly bump into you during the course of a conversation. When sitting next to you at the computer, he will claim the arm of your chair and lean in towards you. Furthermore, my desk is hemmed in on three sides so that if he comes to speak to me whilst I’m sitting there, I’m boxed in.
I could have written off this guy’s tendency to stand so close as a hearing problem, if it weren’t for the sexist jokes that he also makes. This was almost bearable until last week when I was standing next to him as he sat at his desk. He was holding a map between us at the height of my pelvis and when he went to show me a direction on the map with his pen, well the repeated movement also implied a number of other things . . . I don’t think he was oblivious to the connotations of what he was doing, but it would be very hard to convince anyone that he wasn’t just innocently showing me something.
Now, once again I find myself not wanting to cause a scene and get one of my superior’s in trouble. Every time he does something that bothers me, the question pops up “was that deliberate or unintentional? Is he standing close because he’s awful or because he can’t hear me? If it’s a deliberate attempt to upset me, how do I prove that?”
So empowered members of the feministing community, my question is how do I handle this man? What tips do you have for keeping someone out of my space without making a scene?