if you cant find them online you might be able to trade a few homebrews or something to someone on these forums for a rhizome cutting from a well established chinook plant. unfortunately although I have a chinook its not doing to well so cutting the rhizome might kill my plant not to mention if it has a disease ill be giving it to you. But maybe someone else will make an offer.
I dont know the exact procedure but i think you can just cut the rhizome in half and both will grow into genetically identical hops.