lash bloop

So, if I am doing a cam change and want to stick these new roller rockers on at the same time, how do I set the lash or preload initially for cam break-in since the lifters have no oil in them yet? The setting will change once they have been run thru the break in procedure, right? Is there a way to set them or do I have to assemble the old rockers to break the cam in, then take it back apart to put the new rockers on? I don't want to blow the break in, or mess up my rockers and new rods.#-o