I love this move. The trick is to use your legs to throw your momentum forward. I climb up, get a bit of speed, then set up my top hand quite high and my bottom hand on the pole near my waist. Once my hands are set up, I take my legs off so they're straight and hanging next to the pole. From here, I sort of flick my legs back and then forward and release the bottom hand. I can only do this if the top hand has excellent grip. You need to trust that your top hand will hold. Also, you need to create a big push with your legs to get yourself forward. As the pole continues to spin, your legs will find the pole to get into eagle.
You can learn this trick from the ground. My instructor does it here at 1:22.
http://www.youtube.com/watch?v=_Tod11HW3Sc