There seems to be some confusion about the identity of Lecanopteris carnosa in cultivation. Plants from Sulawesi are characterized by spiny outgrowths as seen in the pictures. Such structures are not known from the plants grown as L. carnosa to date. The type collections were made in Sulawesi, which means that the plants grown so far very likely are something else.
All species of Lecanopteris can be grown in an open mix consisting of Sphagnum, perlite, peat, bark and other compounds that enhance drainage. While they grow directly on the bark of older trees, in cultivation growing them mounted on bark does not work too well. Plants tend to grow extremely slow when grown that way. In cultivation all species take benefit from being fertilized regularly using Osmocote. In the wild this job is done by ants inhabiting the rhizome of the clumps. In order to avoid ugly leaf-spots, water should not be standing on the leaves over night.