Well, a simple solvent extraction(liquid liquid extraction) will not be sufficient to separate CBD from the other cannabinoids. Maybe there's a way by really tweaking the solvent phases, though I'm not so sure it's practical and it would take a lot of experimentation. This procedure is typically accomplished via chromatography in scientific literature(be it gravity, HPLC, etc). Which to my limited understanding is a bit of a nightmare with these compounds. Bands like to bleed and chemicals like to group. Vacuum distillation of a nice hash oil may be possible, though it still wouldn't be 'pure'. Is it really worth all the solvent and running 10 foot columns for a few grams? Probably not, beyond novelty.
Maybe there's a solid phase resin out there to utilize the 'catch and capture' technique. The phenolic hydroxyl's look like they want to be massaged into a use. Never-the-less THC also has one of these. Hard to say.
Hypothetically it is possible to genetically modify the cannabis plant to not produce THC and still produce CBD. This is something I know absolutely nothing about.
Best bet for acquiring pure CBD is not discussable on this forum, for just reasons. Vote for medical cannabis when you can, then this will become a more common item. It was in phase 3 trials for psychotic disorders for a while in 2007 iirc. I don't think those ever came to fruition(not a conspiracy, it just wasn't that effective).
Soxhelets are typically used for alcohol based solvents. I see no real advantage to using a soxhelet in this case.