Right now, I’ve only done nodal micropropagation for cannabis. It’s pretty similar to normal propagation, but you need less plant material (just a single node + 1-2 cm of stem below).
Take the nodal cutting from a plant (if it’s not already in tissue culture, you’ll have to sterilize it first) and put it into media containing shoot-promoting hormones. After you get good shoot development (a few more nodes develop), you can repeat the process to get more clones or transfer it to media containing root-promoting hormones and wait for roots to develop. Once roots develop, start hardening the plant by cracking open the sterile vessel you were growing the plant in and over the next week keep opening it further and further until the cover is completely off. Then, carefully wash the media away from the roots and transplant it into soil (or equivalent).
I haven’t done meristem culture for cannabis yet, but it requires much more babysitting, as you’re dealing with less overall plant tissue so it’s a lot more fragile. However, that would probably be the way to go for scrubbing viruses, as that less amount of tissue means you have a higher chance of starting with a piece of plant that is virus-free. In theory, you could scrub a virus using the nodal-propagation technique, but you’d have to put it through a lot more propagation cycles (because the starting material is so much larger).
To get into the specifics of materials and such: The media I use is a combination of MS media (with vitamins) and agar (~7g per liter of media). You should use enough agar so that the nodal segments can stand on their own, but you don’t need to press hard to get them into the media. Autoclave it, then mix in whatever hormones you’re using when it cools to 60 C. Finally, pour the media into your vessel of choice (I use magenta boxes) in a laminar flow hood to ensure sterility, and let it cool.
For hormones, I’ve experimented with a bunch of different ones. I’ve found that cannabis is so vigorous that (when using nodal segments) you don’t need a shoot-promoting hormone, you can get good stem/node development just in the plan MS media. For rooting, it’s more difficult. You can use IBA (the active ingredient in Clonex), but I’ve also had success with meta-toplin.