Try a backflip first, but make sure you can do it on a trampoline, off objects such as benches and curbs, and depending on how big the jump is, being able to do it off the ground would probably help too. I'm sure given enough time and attempts, you'd be able to get it on skis without being able to do it on a tramp or anything, but I would hate to be the guy that says "fuck it and huck it" and then have you make a thread a week from now saying how you hurt your back.
So other than that, good luck and be smart.