I used to not be able to do these but now I can after lots of practice.

You will need to be able to kickflip very good and be able to get them over probably 1 deck. You don't have to be able to do B/S 50-50s, but they can help.

Find a well waxed curb that is about 3-5 inches high. Go kinda slow. Ride almost completely paralell and about one foot away. Start a kickflip, but make it kinda go behind you so that it lands on the curb. That will take a few wuss-outs to get used too. When you can make it land in a 50-50 almost every time you will be ready to start landing them. Do the kickflip and make it go toward the curb. Jump toward the curb and stay above your board. Land on the board only if you see that it is gonna land a 50-50, if it lands upside down you will get a nice rip in your tape. Get to where you can land in the 50-50 almost every time and start going a little faster. Make sure that the wheels are rubbing against the edge so that you will get a long grind. When you get used to that you are ready to come out. Just lift your front truck and do a little kickturn to come off. Practice, practice, practice.