Find a secure slot/gap/crack on the table locking mechanism to install your phone mount. After attaching, make sure that the flexible pieces are stiff and does not fall of.The J shaped piece is meant to hold the top part of the phone. It may not be seen in the photo but I just wedged the end of the J-piece between the tight gap between the fabric and locking mechanism.
Another option is to always bring a portable suction type phone mount (http://blog.alienskin.com/wp-content/uploads/2010/12/Kensington_Mount.jpg) with you while traveling and sit beside the window so you can fix the phone on the window in front of you while on flight. I was able to use this for a few flights but the DIY barf bag project was more interesting and challenging :)