Just purchased this unit and tried installing the 64 bit version for PPro CS5.5 . . . does not show up in the effects window in CS5.5 and does not show up as being installed in the media core set of effects.
When you run the installer try selecting Custom install rather than Complete. Doing so will take you to an option page for which host you want to install to, make sure the CS5.5 is selected. Once it's selected it should show you the install path and allow you to change it if it is not correct. It should be as follows: