i wouldnt even try potting it. ive only ever had them on slabs or old branches, and its easier than it looks beleive it or not, plus, you have to start mounting somewhere. make sure the plant has a good healthy root system, then place it (i always place at the bottom of the slap so the plant grows up) so it looks good, and tie it on firmly using old pantyhose and maybe some sphag for packing. All i do is mist when i go past with the hose and everything seems fine and thriving.
Try it, and if it isnt for you, then, you know for next time