It is possible but it will result in at least a few holes, but most likely many holes.
The skaarj you are seeing isn't subtracted, it appears to be additive but actually its just a decoration that's scaled up in size and probably has a new texture on, if you want something like that, try this, it may take a bit of time the first time doing it
lets say you want to do a skaarj statue, what you could do is this, take a nali statue, and put it in place. The default properties that you will want to pay attention to are:
CollisionHeight: 88
CollisionRadius: 22
bPushable: True
DrawScale: 1
Mesh: LodMesh'UnrealShare.NaliStatueM'
Skin: None
You'll want to change the mesh first, select Mesh and click on the ... thats there, a Mesh Browser should pop up, assuming you want a SkaarjWarrior, just find Skaarjw and then hit Use on the properties. After this you'll want the same collision properties from the skaarj onto your statue, look up the default properties for a SkaarjWarrior and copy them over to your statue. Now a bit of math will be involved, lets say you want your statue to be bigger, mess around with draw scale until you have a size you want, now if you change the drawscale, collision properties will stay the same, so lets say you put 4 as your drawscale, you would need to multiply the CollisionHeight and CollisionRadius by 4, and you'll have better collision. chose any skin you want and put it on Skin, it would probably be best for a Base texture or something like that. Change bPushable to false unless you want to be able to move it. After that you are done
YES! 
