Yep, it's the same as adding a new body, you have to make two archtypes from the static mesh.
I added a gladio sword in one of my maps.
Just bear in mind that pivot must reside at the object center, and most important (i forgot) the object must be set at 0, 0, 0 or it will always be outcentered, before export it,, makin placing and other stuff more complicated.

Yep so,
1)Import your model, fbx format preferably with collision box included. Import your textures for said model.
2)Create a new material using the textures you've imported and edit the static mesh (double click the mesh in content browser) to apply it. If you didn't make a collision box, you can make a one in the mesh viewer whilst you're here popping in the material.
3)Goto the Actor Classes tab in the content browser.Find VCDebrisPlaced, right click it and create new archetype, making sure you give it an appropriate name and selecting the right packe to save it to.
4)Find your new archetype in the content browser and double click it. In here you need to set all the options of your item, Set the static mesh to be the one you've imported, set if the item is held in one or two hands, it's pickup and dropped sounds, if it leaves a splat when dropped, if it's counted as mess or not, lots of stuff to check here, go through the properties and change what you need to change.
5)Go back to the actor classes and make a new "VCMessFactoryDebris", open up it properties (double click in browser). Go back to your content browser and find the 1st archeytpe you made, right click it and select full name copy to clipboard, then in the messfactorydrebris properties paste the text into the "Debris Template" field. Without changing any other options the item placed in editor will look like a gib but will be fine in the map, but you'll want to change that so it looks ok in the editor so go back through the properties making the necessary changes to mesh/sound/mess etc.
6)Place the MessFactoryDebris you've just made into the world, save>test it out.

Hopefully that all makes sense to you.

A note for the collision mesh.
I'm using Max so i don't know if it's the same for other apps, but you need two mesh in your file, the object and the collision who must have the same name as the mesh, don't remember if need the _collision in the name, but when imported Unreal automatically import the collision mesh too.

Yeah in max the collision mesh needs to be called UCX_meshname_01.
In the udk mesh editor you could get away with a 16dop box, since it's not a complex mesh.