Hi Jules,
 
I cant help you with how to keep fuzzies from pooping everywhere in the
cage because ours do it on occasion.
 
As far as keeping litterboxes in place, we use thin wire, drill holes in
the litterbox and tether the box to the cage in several places.  We still
have ones that will try to dig under and on the sides, but they arent
able to move it or get it loose.  This works great for food dishes as
well!
 
Becky and Heather and the Excellent Eight
Missing Ally, Sleepy, Peanut, Mialey, Egan and George
[Posted in FML issue 4818]