Modding

Is there a way to add abilities to war machines? They aren't in GameMechanics\Creature\Creatures. The closest thing I found is the file GameMechanics\RefTables\WarMachines.xdb, but it has a different content structure, and adding abilities in this form yields no results:

< Abilities>
	< Item>ABILITY_MAGIC_PROOF_25< /Item>
< /Abilities>