it's possible it is able to be found at hiveworkshop...some of dota's stuff originates from there, otherwise...best bet is to extract the file directly
i haven't checked jetfanginferno's sand models yet, but i think one of those could be it...let me know if it's one of those or not.
no need to import it, i ran into a question exactly like this the other day, there is dust that shoots up with the impale spell (crypt lord spell from Melee maps), that is the dust used dota, most special effects are vanilla effects in dota, but their coding of it is what makes it great
Finally finding about some of the bots that are flooding the users online - bytespider apparently is a huge offender here - ignores robots.txt and comes in from a ton of different IPs
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.