I love Moss Walls and Just diy'd the siest way possible.
I use Filter Floss Pads.
Cut them to the size you need for the back of the tank.
attach the java/taiwan moss to it. I just left it on top and waited a few days for it to attach. attach to the tank using clothes pegs, bulldog clips, massive plastic paper clips from the 99pshop, just plain plastic coated garden wire bent to hold it in place.
The Filter Floss creates the best rooting platform and willalways keep it moist.
Plus the Filter Floss acts as extra filtration and my shrimp love hanging onto it,
I use these in my fighter breeding tanks and the females love it as there hiding spot.
I also use this idea for attaching to slate and when i made the waterfall for the crabs.
i'll get some pix uplater.
HTH