I tried using the bath pouf (technical term for "scrubbie", lol) and it didn't work so well for me. My bottom dwellers kept getting tangled in it. You may or may not have that problem with shrimp.
What I did was to take dark colored cotton thread, placed the moss (I used riccia, same difference) on the driftwood, and then wrapped the thread around the driftwood and plant a zillion times, criss crossing, etc. Then I just tied the end to one of the loops. This worked beautifully for me for months until my riccia died b/c it became choked w/ algae. I never had a problem with the thread rotting either. Every month or so I would take it off and re-wrap it because my riccia used to grow like crazy. Moss, I would think, may attach to the rock after a while and you wouldn't have to worry about it anymore. I have no experience w/ that though because I have killed three types of moss in my tank - it just doesn't grow for some reason. LoL