Pallid Crystal and undead question

[Wilamac]

If an undead creature is wearing the Pallid Crystal magic item (Gods and Magic page 59) does that make it immune to channel positive energy. I think it would change positive energy to negative energy healing it but would it still need to make a Will save to avoid fleeing, or would it have to make a Will save or become controlled by the channeler? I have a cleric necromancer in my group and was thinking of using the item but wanted to get the rules straight before I give out the item.