Persistence. In all honesty thats the only thing you need in order for them to get into it. Sooner or later it will become their space, but the more you change all the time, the longer you will make it for yourself. You need to have it set up the way you will have it set up all the time. The reason is simple, if you leave the light on then thats fine, but then once they are used to the crate are you going to switch it off? If so, you're likely starting again. Smells are a good thing, as eventually it will be replaced by their own smell anyway, then it will become their space. Covering is fine, as long as you are going to do so all the time from then on. But most of all, its persistence. It's a pain in the backside we've all been through at one point or another, but it will calm eventually.