For this trick, you ought to be comfortable with frontside boardslides, and backside tailslides. Just be comfortable with turning your body, and keeping your head straight.

Approach the obstacle frontside, with a moderate amount of speed (how much depends on how slippery the obstacle is). Ollie, and smack your back wheels on top of the obstacle, and your tail against the side. Your body should turn with the board, but you should still be looking forward. To slide, you want to push with your back foot, and keep your front leg bent.

To come off the end, you can simply turn off and land. Coming off in the middle, though is a bit different. You have to ollie out, and bring the board off and around with your front foot (ollie out off the end for bonus style points). Land with all 4 wheels at once, don't shred, and roll away stylin'.