I find a 540 hook kick is easier. A great tip for any jumping spinning kick is stay tight. Keep your arms in close to your body...kinda like a figure skater.
Also, just work on the jump and the spin...then add in the kick. If you attempt the jump and kick at the same time it could cause it to be sloppy with bad technique. I've done a 540 hook kick speed break before. My next goal is a 720 lol.
I would suggest practicing this kick on a set of mats. When I first tried it, I didn't use mats and at my school, we train on a hardwood floor. My heel slammed into the ground because I was spinning sideways and my heel was swollen for a week.
I hope my tips help! Just remember...break your kick down into smaller parts. Jump and spin first, then the kick. Try and go a little further than 540 when you're practicing then it might be easier to control when you take the extra spin away.
Try using a jumprope too. It'll help with your jumping abilities.