Here's an exercise from Matthew Sweeney's new book Vinyasa Krama ( I look Mathews book more closely here http://grimmly2007.blogspot.com/2008/09/matthew-sweeneys-new-book-vinyasa-krama.html), he has a long, in depth, section on Back bends that covers half bending, the Drop back and Tic-tacs.
"To begin half-bending you should lengthen the spine on the initial inhalation; you can raise your hands overhead or keep your hands on your chest or hips as you prefer. on the exhalation begin to move the hips foreword , gently firm your abdomen and then extend your hands to the wall. At no point should you fall onto the wall. Attempt to hover with your arms extended and your fingertips a small distance away from the wall (taking an extra breath or two as necessary rather than holding your breath) and only then touch the wall with your fingertips and bend your arms. i prefer students to land on the wall with their fingertips as this encourages lightness, rather than a stiff-armed jolt. once your nose is near the wall you can either come up immediately or stay there for a few breaths. remember do not walk your hands down the wall."
Coming back to standing you extend your arms pushing gently off the wall inhaling as long as possible (taking extra breaths if necessary but don't hold your breath) and with your head back the whole time. Hover again if possible when your arms are stretched and then roll the arms to the side rather than back over the head which would unsteady you .
I really like this exercise. The wall is there to remove the feeling of panic allowing you to focus on breathing and weight distribution. Think this will be good for coming up as well as for Kapotasana.