No need to steralize the rock at all. Personally I wouldn't even dry it out. Simpley put in a few pails or large rubbermaid bin with a powerhead and heater. Leave it like that for two months and add bits of food a few times a week. It will allow the ick to die off and preserve rather exspensive rock.
If your intent on drying the rock, once it's completely dried naturally, just leave it a week like that. Since it will be dead rock anyway, soaking it in RO
water a week or so will accomplish the same thing.