Modding Seige Equipment?

Is it possible to make any changes to Seige Equipment? i.e. Battering Rams, Ladders, Seige Towers, Sapping Points.

Specifically what I'm hoping to be able to do is disable some of these items, preferably only for some factions/cultures.

What about changing the build points required to construct them? Can that be done?

Thanks.

Or here's a thought, I could have a decent look before asking.
Data\descr_engines.txt

Thanks anyway people :p

(I'll let you know if I pick up anything of note)

2 other files that will need to be looked at to change cost and who can build
both also in the data folder.

export_descr_buildings.txt (what building and which culture)
export_descr_unit.txt (cost and attributes)

cheers,
B.

Well unfortunately my problem remains. The descr_engines.txt file only relates to how seige equipment appears in battles, but has no relation whatsoever to the strategic interface.

The export_descr_units.txt and export_descr_buildings.txt files unfortunately have no references to seige equipment (battering rams, seige towers, ladders, and sap points) in them. They do have artillery (onagers, etc), but that's not what I'm looking for here.

So I guess this turns into a request then. CA, any chance that we might be able to in future alter who can build what items of seige equipment? Twould be muchly appreciated, at least by me. ~:)

Or if there is some way to do this already, could you point it out?