The easiest and most straightforward way to do this is to make sure the mesh you’re importing is located in the same location as your Monolith model (generally around the origin). Also, scale is important. But, assuming you’re model fits within a 2x2x2 cube and is centered about the World Origin (0,0,0) then it should import directly within the default boundary volume. You can of course resize the boundary volume to any dimensions you want using the Resize dialog box under the Main tab.
An alternative to this method would be to assign an Affine Transformation to your mesh. You can do this by first adding a layer to your stack called “Layer Composition Stack With Affine Transformation” found under the Group category. Once you add that layer you’ll see a small circular arrow on the far right of the layer tab. Click on that and it will roll out a secondary panel that has an area called Transform Stack Layer. Simply drag and drop your imported mesh layer into the brackets under the Transform Stack Layer. Now, if you change any of the parameters of the parent transform layer (click on the cube icon shown on the parent tranform layer), it will also apply to the imported mesh. I’ve attached a screenshot of a quick example. Let me know if this help.