How can we disable Tower Fire in sieges?

AI is very dumb and never conquer towers, so they lose a lot of men inside walls with defense tower firing...... That sux and i prefer to play without Tower Fire at all, or if possible (and the ideal solution) without Tower Fire to inside town!

Do you know how can we do it? There are any mod to it? Or do you know where we should rewrite to remove it?

Thanks,

The people on the LotR Total War Team took away the towers, that would do it.

Disabling Towers