I don't think Mind Blank would block True Seeing, as it only blocks intrusion into the mind. True Seeing has no effect that would allow the caster to get into the target's mind; it only reveals physical truths. If True Seeing slightly more mystical knowledge as part of its effect (Know Alignment, or Detect Insanity, or the like), then I think Mind Blank would work.
OP, what are you specifically trying to get past True Seeing? Is it a disguise of some sort? If so, then just use the Disguise skill. True Seeing can't penetrate NON-magical disguises, just magical ones.
As far as true counteraction (and not dispelling) I think it would have to be a carefully worded Wish or Miracle spell.