Holy water. By the gallon.
Or you could invest in a wand of cure __ wounds, like PCat suggested, and the wand of searing light's not a bad idea. But you could, if the DM would let you, use cure potions as grenade-like weapons. Take Quick Draw as your feat and start throwing.
But, as other people have said, sometimes it's best for a rogue to do distraction duty when fighting the dead. One question, though- are you going to the undead, or are the undead coming to you? If the latter's the case, some ranks in Craft (traps) and a cleric buddy (for spell traps) would put a dent in the undead's day.
Demiurge out.