If you have XmlSiege installed, you can spawn an wall with the itemID. So on an Xmlspawner the entry would look like:
Code:
static,0x33/ATTACH/XmlSiege
Now that just attaches the basic siege properties to a wall, or whatever you're spawning. If you want to get more detailed, like how many hit points for that item, you can set the properties for all Siege variables right on the spawner, like this:
Code:
static,0x33/ATTACH/<XmlSiege/Hits/100/HitsMax/100
There are several properties you can set, including the DestroyedItemID (what the destroyed item turns in to once its destroyed). Just make sure you use the , in front of XmlSiege like I did in the above code for whatever Siege properties you want to include (if you don't set any, you will get the defaults).

The other way is to use the ADDATT XmlSiege (then use GETATT on that item to change properties) and target the item you want to be destroyed. Now this is ONLY for items you've already placed. If they are tied to a spawner, once destroyed, they will respawn without the attachment.
 
its possible convert all the map structures to xmlsiege?
Yes and no...most deco items are created as "untouchable" statics by the Decorate command. You would have to edit the decorate maps for whatever facet you pick and then respawn the structures with an Xmlspawner to attach siege to it.

It's a lot of hassle and it would be very time consuming creating addons for all the structures you wiped off the facet, but if you really want all structures on a facet to have the siege attachment, that is the only way that I know of.
 
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