An established system can accept small ammounts of live rock at a time, or you can cure a bach of live rock in a seperate container before adding it to the aquarium.
Ich won't be removed by mechanical or biological filtration. Some people find UV effective, it can kill ick in one of it's life stages. (Some others don't approve of UV, as it may kill benificial critters as well, but most people who try it like it.)
Have you tired feeding garlic? Have you left the salinity at 1.009 for the full 3 weeks? There has to be a reason why your fish are stressed enough to come down with ick. A healthy, unstressed fish should be able to fight it off.