It's not gonna the same consistency as hair wax, but if it's really too hard to get onto a rag stick it on a radiator or something for a while, that should soften it up. A little goes a long way, which is why you don't really need it to be that hard. A brush is a good idea though, because it will give it a more even finish, and if you have excess wax on the ski it's only going to slow you down.
My ex-racer knowledge comes in useful when it comes to ski prep! haha