PFSRD: "You threaten all squares into which you can make a melee attack..."
Compel hostility: "Whenever a creature you can see that threatens you makes an attack against one of your allies, as an immediate action, you can compel that creature to attack you instead."
Double-checking the total concealment and invisibility rules as well, what I'm taking away is that you can still be threatened by an opponent who can't see you, they just can't take their attacks of opportunity you'd normally provoke. So then what happens if you use your technically-threatened status to redirect attacks to yourself via compel hostility, when you are invisible? I see a few possibilities, plus I could always have missed some...
A) Compel hostility only requires them to redirect their attack in an attempt to attack you, and gives them no benefits or knowledge in doing so (except that enemies who know how the spell works will know you must be in their threatened area), leaving them to have to guess which square you're in, thus making you almost impossible to hit.
B) Compel hostility redirects their attack to your square as part of its functioning, negating their need to guess a square but still applying your full miss chance from total concealment.
C) Compel hostility redirects their attack to you directly, negating your concealment entirely by virtue of your sudden attraction of their weapon (although you still get the benefit of AC normally).
I'm personally leaning towards B myself, though a strict rules-as-written reading probably indicates A. I'm not interested in cases that specifically focus on the invisibility spell; if I do use this (admittedly cheesy and slightly exploitative) tactic, I will almost certainly be using a different means of obtaining total concealment. (Actually, I will probably only have normal concealment, but an enemy dangerous enough to pull this tactic out on is likely to have reach...)
Rules-as-written are nice, but extrapolations or designer commentary are great, really anything as long as your assumptions come from somewhere.