I agree with fufalump, just keep practising them on a grassy area. if you fall, its just grass, so try it again and again till you get comfortable with the motion and eventually youll get them.
Fat seat. Up high. virtually standing still. start with half barspins. chuck the bars (my personal fave instead of guiding). maybe wear knee pads at first or the inside of your leg will get rubbed raw and guaranteed one of the times the timing will be off and you'll chuck the bars straight into your knee.
Once you have the 1/2 barspins down it is just a slightly bigger chuck in a slightly bigger bunny hop.
bunny hop as high as you can ( while keeping control ) even out, lean back and whip the bars as you are going down, release the bars when they are aligned with your top tube to make sure they do a full spin and catch with the opposite hand. its a great idae to practice on grass too lol, hope it makes sence.