1. place your front wheel on the obstacle :P"
2. be diagonal to it, with your weak foot close into the obstacle
3. stand tall, towards your bars
4. hop, or do something to gain your balance WITHOUT the rear brake on...
5. crouch down towards the back of your strong foot.
6. jump up and tuck your back end up, while extending your arms at the same time.
I find it easier to do it without a back brake on, and without a pedal kick.
Also, you may find it easier to do this with your front wheel on the back edge off the obstacle, so you can have some more tyre spring to help.
also a low and long front end will help you to master the manoever :(