A lot of my EVs were wasted on Snorlax, because he has a reasonably high Speed (don't ask; I don't even know how). Anyway, I'm in Laverre City right now and am wondering if I can get my hands on those berries.
You obtain them by mutating berries, which basically involves planting specific types of berries next to each other, and then it has a chance of giving you a certain EV berry (and some others too). Untill now we know the following combinations:
Mago + Iapapa = Pomeg Chesto + Persim = Kelpsy Sitrus +Lum = Tamato Aspear + Leppa = Hondew Aguav + Figy = Grepa Oran + Pecha = Qualot (and some other non EV berries, not listed)
Source: http://www.serebii.net/xy/berryfields.shtml