Figured something better out - There are 2 Spells that wll prove invaluable in this -
Hide from Undead - Cleric 1 - Becomes for ALL purposes undetectable by undead. Best part is, Mindless undead don't even get a save. You can't attack the undead, or cast spells at them, or anything like that, but they won't even notice you. Duration is 10 min/level, and it effects 1 person/level with each casting. If the undead show up before the Kythons, you'll just have to continuously cast this through a wand, until they show up, then hide from the Kythons and watch the Undead and Kython fight. Alternatively, cast it on some fast people, who bait the Kythons into running right into the Undead ranks. They can jsut run in between the undead, and the undead will form a protective wall so they can flee back to town.
Command Undead - Sorc/Wizard 2 - Short range, LONG duration (1 day/level.). Allows you to command the undead to fight for you. Again, no save for Mindless undead, so you can have the undead attack the Kythons and later have them commit suicide (the spell strictly states they will do so). Make your enemies your allies - Just make sure you have wands of this on hand too, to possess the Stronger Kython zombies when they die.
In other words - Make them all Clerics and Wizards, if they have even 12 Wis/Cha. The others can be Rogues with Max ranks in UMD, or other things that can shoot from a distance and run like crazy. This will not be won with the villagers in melee.