Hello! The standard snow-covered rocks are available in the "MyRocks" folder, labeled "<insert rock type here> 5". The ice rocks, however, are intentionally not there for you to use. However, they do use two textures from the terrains files "ice 2" and "ice". To assign these textures to the rocks, you'll have to open up the rocks .material file, copy-paste one of them to the bottom, give it a new name, and assign the texture as one of those two. If you like, you can copy-paste the textures themselves into the "rocks" folder. Then you'll go into Object Maker, load a rock, and then go to the second tab labeled "mesh," and change the "material" line into what you named the material for your ice rock. Save it with a new name either into your MyRocks group or create a new one, and voila! You now have ice rocks!
As for the actual snow piles that surround the portal in Ficho Tunnels in case you would like those as well, those shouldn't be too hard to also make yourself. Take a snow texture from the terrain files, do the same thing you did for the ice rocks. Only now, before you save it, on the "Mesh" tab there should be a checkbox that says "own collision" and is ticked off. Go ahead and turn that off, then save it.