baker, if you're using points rather than triangles/polys, you're doing it the lame way.
you can find the correct(afaict) maths for an even distribution in eg fte's R_Clutter_Insert function. no need to subdivide that way, and you don't get particles spawning within walls either (excluding fpu precision, anyway).
the idea of quakespasm with effects like https://www.youtube.com/watch?v=q-rO8haGoh4
(please excuse the bugged gloss, that's an ooold video) and yet no texture replacements kinda makes me laugh.
at the same time, the idea of a load of cubes or quads or circles or whatever doesn't fill me with confidence either.
regarding csqc, the idea of that without any other qc extensions nor replacement textures is also a bit of a joke, at least for everyone but the guy trying to use it, who would get too frustrated to produce anything worthwhile.
really though, if you want an engine with a decent particle system and decent csqc etc, then just use an engine that already has that stuff.
in all seriousness, a low-res weather system is imho just going to look as goofy as eg the gloss in that youtube clip. sure, its interesting to do for the sake of doing, but I'm skeptical about the results and repercussions.