i dont know if this would work, but for like courses and stuff they use salt to harden it up, you could try packing it a little, salting it, then packing more, and salting again. it could work, but i have no experience doing this sort of thing.
you can build a jump with powder it just takes a lot mor work. the snow needs to be packed a lot so it takes longer and it is a good idea to let it sit for a couple hours after you build it. but if you are not building a huge jump you should have no problem.
What you do is shovel off the powder till you get to the harder snow then you take the shovel and cut out a block of snow until the jump is big enough.