I used rock from my tank from 4 years ago. The thing is, I don't know if it would qualify as dry or live. It was stored in a refugium of sorts, and still had living algae when I got it out. How in those conditions I will NEVER understand. Anyhow, I've seen different methods from cycling it in a kiddie pool to just bleaching it. I went somewhere in between. Vinegar mixed 1:4 with dechlorinated water with a pump out in the sun. filled up slowly until mixed, then blasted full pressure with a high air content setting on the hose (firehose type) for skimming affect (LOTS of microbubbles blasting that vinegar around). Left that for 30 minutes to soak, came back out and pressure washed each piece individually making sure to leave no algae or dead organisms on the rock (except skeletal remains of a few encrusting corals :( ). Finally I left that out in the sun to dry for 7 hours, and then arranged in tank with just freshwater. I let that sit for a day with the skimmer on to ensure I didn't miss anything (keep in mind this skimmer is long since broken in) With almost no accumulation of organic matter, I mixed up the salt and set off on the journey from there. Seems to be doing well so far with no nitrate or phos spikes, and salinity and PH (the one I was worried about due to vinegar) are staying stable. Temp is fluxing a bit, but I'm running heaters I never ran in the 30 before... overkill for it really (dual 150w).
Happy to be taking this journey together! LOL. Let me know if there is anything you need along the way and I'll be happy to help if I'm able (I still have quite a bit of base "dry" rock as well) :D I need to go pickup some live rock to seed with and a CuC soon