I'm not too familiar with Dread Necromancer (read a bit of the handbook), so this is just general thoughts. I tend to like the ToB classes for the melee halves of gestalt. Crusader would probably best fit for the CHA synergy and he can use white raven maneuvers to direct his hordes of undead where they'll be most effective. Possibly also a version of devoted spirit, but you might have to change the healing maneuvers to harming maneuvers so they heal you and the other undead. If you're ignoring xp penalties or are human, two levels of unarmed swordsage and then ascetic mage feat might also help. (and/Or wilder for elude touch, but that may be a few too many random base classes).

Anyway, if I can come up with something more concrete, I will.