Selaginella lepidophylla, though sometimes mis-identified as Selaginella pilifera, is a native of New Mexico, Texas, and Northern Mexico like S. pilifera but is a different appearing species. While I have tried this plant I believe the issue with growing it is that no one really knows how! But looking at its habitat and understanding the type of climate that the areas of occurrence have may provide some clue to some measure of success.
One British site I ran across recommends soaking only the top of the plant and not the "roots" (these are actually rhizoids.) This makes alot of sense. What also makes sense is planting these babies in granitic gravel with possibly some sand and some acid plant mix-guessing by volume: 70% gravel, 20% sand, 10% acid plant mix. Get the sand and soil mix damp before mixing into the gravel. Find a clay pot just large enough for the plant to sit in and have a little room to pour in the gravel mix. Hold the plant so the rhizoids are just below the lip of the pot and pour in the gravel mix and pack in with a dowel and pour in to fill to the brim of the pot. Do not water EVER. Instead using either rain, distilled, or r/o water in a spray bottle just LIGHTLY spray a coarse mist on the plant leaves. and sit in a shaded spot. Keep your spraying to only two or three times a month during summer in the northern hemisphere and either not at all in fall, spring , or winter or perhaps once a month.
What you want to get is some of the leaves to uncurl. What you expect is that new rhizoids will form from whatever leaves uncurl. The old rhizoids are dead so do not expect them to soak up water as they are not roots, and only serve to hold the plant in place. All water absorption is done by the leaves.
So don't push the plant and maybe it just might make it. Please note I am only guessing at this time and hope to try this method out in the near future. For plants check out eBay.