Even if it is in a tank...the die off will be such a magnitude in which a 30% change of water wouldn't effect the cycle part...
When I cure live rock, I do it in buckets with circulation, heat and air...I change the water about 50% every 3-4 days, and scrub the rocks before the change with a nylon brush...I keep the heater set to about 82 degrees to aid in the process...
Personally, I never have, nor ever plan on curing live rock in a new tank...