Little bump to this thread with a quick (getting longer daily... sorry) synopsis of the most salient info, for any new viridis growers ...
For soil, use the "Bach mix", which is about 1:1:1 potting soil: perlite:vermiculite. They can go a little heavier on soil as they mature, but the lighter mix is good for rooting. They run the risk of transplant shock, so any changes in soil should be done gradually.
Leaf orientation: People have had success with planting the leaves horizontal, vertical or vertical with much of the leaf buried (see image below, courtesy of hcc). Each seems to root successfully, though it is more likely to have sprouts growing above the soil line with vertical. You can also snap the main stem in several places of the below soil part (accordion method) for any leaf orientation to promote shoots in each spot. You dont't tear it apart completely, just snap the stem and plant same as otherwise.
Humidity is key. You want near 100% humidity because this is going to take awhile and the leaf needs to stay moist to stay alive. Anything from putting the pots into large ziplocks, covering with glass jars, plastic 2-liters, up to more complicated humidity chambers should suffice.
Supply fresh air daily or so (though they've been left to go longer without issue) by opening up your chamber for a few minutes.
Water thoroughly, and keep them moist throughout rooting. Don't let them dry out between waterings, though with the high humidity you may not need to water very often at all.
As for light, PV are understory plants. They are highly susceptible to burn with too intense of lights. They do fine near a window (I'm using an East-facing window) or on the outskirts of an indoor light setup. Outside as they get older, they'll do best under a tree so they get a couple hours of indirect light early or late and are shaded during the high-light hours of the day or under a partial shade cloth.
Temps in the high 70's to 80's are preferable, I believe, but attaching a heat mat or heater to the chamber was unsuccessful for TBM and fried them. I rooted a leaf bit my cat left after he munched a pv in downright cold weather (indoors, but drafty and well below their preferred temps), and it has finally sprouted despite the colder temps.
Then wait. And wait. And wait a little longer. And wait just a bit longer, and... sprouts!
Let me know if anybody sees anything I've missed or should be amended. Thanks!