I'm pretty sure you can frag them just like a normal mushroom ( razor blade through the center, cut the head off the foot, etc ). I think you want part of the mouth on each frag though so you want to make sure you cut fairly accurately. If you want to just move some, you can use a chisel/screwdriver and slowly chip the rock away where its attached. Once you get it loose, just glue the rock chips its foot is still attached to another rock.
If you decide to frag, there's a good thread on here from LazyLivin (if I remember correctly) about how to get the frags attached to rocks.
If I'm wrong, then someone please correct me. I fragged my regular red mushrooms like this and it worked pretty well.