There's a bunch of ways to frag shrooms =P. They are pretty hardy little buggers. If you want to be safe about it, you could take and cut it's top off; you can cut the top up into 2-4 pieces and net it to a rock to attach and the stump will probably regrow into another one. Otherwise, try putting it closer to a powerhead in stronger flow to agitate it a bit and normally they'll move and leave a trail of little ones behind.
They were one of my first corals and now I have random red shrooms throughout my tank. I really like them =).
Good Luck; just a heads up, they are slippery little buggers!
