You could set their datablock to allow jets, but I don't think the zombies would actually use the jets or have AI to cope with the ability to jet. (they might just permenantly fly upwards)
GODLY ZOMBIES
so... if zombies float to heaven, but zombies can't enter churches due to them being unholy which means they aren't godly BUT if they float up that means they are godly... wa-*head asplosion*still, awesome idea