You should have it built in via:
ServUO/Scripts/Items/Damageable/DamageableItem.cs
You can set the ItemID's to whatever you want it to be. It's constructor can take ItemID's like:
DamageableItem(startID) //Starting ItemID only
DamageableItem(startID, halfID) //Starting and half destroyed ItemID
DamageableItem(startID, halfID, destroyID = -1) and finally Starting, Half, and Destroyed ItemID's
so for a wooden wall for starting ID it'd be:
[add DamageableItem 7
If you props it it has many options for how much damage it can take ect.....