Yes, you can do it, as documented in the new Rhacodactylus book. You just have to stir the soil regularly so that it will function somewhat like a compost heap, and male sure the potting soil doesn't have any harmful additives. Better yet, if you can stand it (not for me), add a few bugs on purpose to the enclosure -- I think it's African millipedes that are recommended. Also, misting twice a day should give all the humidity that the plants and cresties need under normal conditions, so if you add a third misting (wake-up time, bedtime, and hoe from work or school time should be good), you should be set even in unusually dry conditions. I would suggest using an enclosure with solid sides for better humidity retention, though, rather than mesh.