I'm going to echo what everyone else said, but hopefully so you understand. I'm not trying to make too many assumptions, but if you're asking how to build a booter in the BC then I'm guessing you haven't built all that many.
1) Find a good location. This is absolutely essential. Find a place with a good hill for speed and then scope out where you'd like to land. Hike up above the spot where you want to build and see if you'll have enough speed. If you're all good with speed and you've got enough run out so you're not landing flat...now start building.
2) There is a lot of guessing on where exactly to build, but you'll want to establish some parameters. Do you want it to be more of a booter (less poppy) or more poppy. How tall are you going to build? All of those questions, and be realistic. All of us saying "oh, I'd hit that" when we watch movies and edits, but be reasonable about your abilities.
3) Once you've found the spot, you have enough speed and you know what kind of jump you want to build, it's time to dig! Assuming there is enough snowpack, you'll want to dig down into the snowpack to find the harder snow. Start making blocks of snow, I usually go 1x1' or at the most 2x2'. I always start by making an outline of the jump with the blocks. You'll want to go wider than you think. Once I've stacked blocks and have an outline, I start filling it in with blocks.
4) You've got an outline, it's filling in, now step into your skis and start packing that snow together. You can worry about aesthetics later, right now you want to make this jump nearly bombproof. Have your friends start stepping up (with skis on) the in-run, then have them slip down it to create a nice in-run.
5) Keep packing and adding more blocks where needed until you've got it where you want it. If you want your jump to look good, take an avi shovel and make them vertical.
6) Guinea pig it and giv'r
