I have not specifically tried it, but I'm also not positive what type of moss you are talking about.
Many people avoid the use of peat moss because it has a very low pH, and the acidic nature has the potential to harm amphibians.
If you are using something like "sheet" moss, you are probably more than safe, as its just a normal plant (that is already on its way out, so it will eventually turn brown and need to be replaced. Before that happens, its best to replace it.
Another kind of moss you can use is Java moss if its available to you. Its what I would call a semi-aquatic plant, being able to grow completely submerged in an aquaria setting, but also can grow up out of the water as long as it is kept very wet. So depending on the type of salamanders you are going to use it for, this can be the best type of moss to use.